It depends on what you consider the benefits to be and what kind of cookware you want to use. One of the things that much gas cooking does is heat the kitchen. At least with induction for most of it, you would be getting most of the kitchen heat from the pots, rather than pumping heated air into the room as well. Induction is also a lot easier to clean up and it doesn't require a double boiler for delicate sauces, candy and chocolate. There are many safety features. It does require iron/steel cookware (or clad).

You can use any cookware with gas, including glass, clay and copper/tin. While it is possible to use induction for wok cooking, with some adaptation of form and/or method, gas is much more suitable. If you use more than one wok at a time for your ethnic meals for 20, you might prefer gas. You can char peppers and eggplants right on the flames.

I have 24" induction (one large double ring, one regular, and one small) and 15" gas (one medium burner, one small) in a set up very similar to what you describe--48" with a couple feet of counter on either side. This is what I can tell you. 36" + 15" = at least 52", given the very minimum possible spacing, which is usually an inch. Considering that the units won't match and have support structures that are meant to hang together, it's probably more. Mine are about 4" apart. The contractors are all cautious by nature, and that might be overkill, but my cooktops are completely and solidly supported. It's possible that you could find a way to trim. Maybe use metal supports or something. But if you want to fit two units in 48" the most you can do is 30" + 15". That's nominal. A lot of 30" units are over 31" in reality.

I was originally going to get dominoes but chickened out and went through some angst in coming up with a plan. I tried to make a 30" rangetop and small induction unit work, but it was too tight. Meantime, I really resisted the lower powered 15" gas cooktop, but it was the best fit, once I found my 24" induction in Europe (online). People on GW have done a full on gas range with dominoes on either side, or on one side, but they had longer runs to do it in.

Remember that you also need a vent hood over the whole shebang, and it should be a few inches bigger than your cooktop area on either side. Another advantage of what I ended up with is the hood gives full coverage at 48".

I'm glad I have gas. There are some things I use it for because I do want the heated air, like toasting tortillas or grilling sausages. I also use it with my old non-induction stock pot for feasts, along with the steel ones on the induction. I don't use it much. I don't use the gas in a power outage because they seem to be localized (only the neighborhood, so one can decamp) and I don't want to spoil the food in the coolers by opening them and letting the cold air out.

By far and away, I mostly use induction. I discovered GW because I assumed I was getting a large range top with a French top, and was doing research. I learned here that I didn't want a French top. And I learned about induction for the first time. At that time, there were very few available in the U.S. and a lot of forum members had gotten ones brought in from overseas without any service or warranty. (By the time I was ready to buy, there were lots to choose from. I only brought mine in for size. It's 2/3 of the standard model sold here, and I had advice from the local service company.)

If you just love the flames and heat, go with bigger gas. If you have a lot of outages, or want to wok, go with bigger gas. If you're not sure, get a cheap portable induction unit to try, and use it as much as you can, knowing that it's not nearly so adjustable and powerful as a built-in full on appliance. That's what convinced me. My portable is crappy, and still wooed me away from my old gas stove.

I say all this because I think you might be happier in the long run with 30" induction and 15" gas. :)

pillog, I hope the fact that I really want to hug you right now doesn't freak you out too much; this reply was hands-down the most thoughtful and informative one I've ever received in any forum of any kind.

I want to be open to induction, and my cookware collection includes plenty of suitable options. With regard to venting, I've planned it out so that I can cover the span AND take advantage of the two smallish windows I demanded on either side of the cooktop area (who doesn't like opening as many windows as possible in a kitchen?).

You've inspired me to futz around and see how induction and I get along. I'm going to ask my husband if he's okay with me switching my current cooktop to our downstairs kitchen and buying a reasonable full-size induction to conduct some experiments. We've got a second kitchen planned for the new house as well, so if induction and I don't fall madly in love with each other, I'll just park it down there and renew my vows with gas!

Thanks again for sharing your experience, your advice, and your thoughts. And for being awesome, obviously :-)

You're very welcome!

Re the windows, with a good hood, you'll have make-up air coming in the windows, rather than effluent going out of them. That's actually a good thing. Do try to have a good ratio between hood and cooking area though. Remember, there's a margin under the hood that's solid, supporting the filters, so there's no draw at the edges, but the plume going up from the pot is cone shaped, and widens as it rises.

You do need to plan for make-up air, and if you're in a place that gets very cold or very humid, you might want to have conditioned make-up air. If you have a really good hood, especially on induction, and good make-up air, you'll open the windows to hear the birds singing not because you need open windows in your kitchen. :)

Your plan for trying induction is a good one. There's nothing like a period of time spent cooking on the real deal. Since you'll be having two kitchens in the new house, however, another approach might be to have one gas and the other induction. :) Though with all that ethnic food for 20, you might also like to get 30" of each under one hood. :) If you could give it the space....

Best wishes for the build.

48" of cooktop width can also be fitted with four 12"w cooktops of various sorts, or two 24", or one 24" and two 12". Wolf has a very nice 24" induction cooktop (CI243CB); rather than trying to squash 4 burners into a small cooktop and winding up with small burners and cookware crashing into each other, Wolf wiselly used only 3 burners which left room for a 10-1/2" and two 8" burners without feeling cramped. You could put a 12"w single gas wok burner to one side - a Gaggenau VG231214CA or a similar unit from Miele - CS1011, and an electric 12"w grill on the other side, like a Gaggenau VR230614 or Miele CS1312BG. Or put the two 12"w units together on one side and the 24" induction stovetop on the other.

If you can use a 15"w wok or grill, your options expand considerably, including matching Wolf units. Alternatively, if you don't want a grill, you could combine the 24" Wolf induction cooktop with a 24" gas cooktop with 3 or 4 burners from Gaggenau, Miele, Smeg, Fagor, Verona, and others. Or one each of a 12", 15", and 24", or a 15"/24"/15" setup. Lots of options.

Wolf 24" induction cooktop: (turn up the brightness if not clear)

The Wolf 24" must be new. Maybe they've been reading my posts and thought to offer something American :) Three rings is standard, though I think a 24" is better if it has a bigger double ring, like mine. The Wolf is certainly adequate if you want to go with a 24", though.

If you read the installation specs on all those units, you'll find that even the ones that are meant to be used together need a connector strip, which usually takes up an inch.