I use a round Lodge cast iron griddle on my induction cooktop. Its perfectly flat on the bottom -- no ridge.

I think you could use a rectangular griddle to span two hobs if you could find one that was flat. The nice thing about cast iron is that it holds heat so well and if you preheated the griddle on the burners long enough you probably wouldn't have cold spots. It also depends on the burner configuration. My 36" cooktop doesn't have 2 large burners next to each other to bridge. I'd have to bridge 1 small and 1 large. With the continuous grates on a gas stove I think you get better overlap of the flames for bridging.

I've never used one of those disks. I read some reviews where they don't work so well.

Did you do a search in the appliance forum? There was a good thread on this not that long ago. Someone had induction that actually handles small lips fairly well.

I have searched, but just didnÂt find a definitive answer. I was hoping that someone here as actually tried this. I just canÂt noodle through why it wouldnÂt work.

The thing is, I am leaning toward induction, but I love my Lodge 20 x 10 cast-iron grill/griddle. And, wouldnÂt you know - itÂs the only piece of cookware I have that a magnet will stick to and it looks like it still wonÂt work. :-\

IÂm going to the garden to eat some worms...

If you can't part with that griddle, LG makes an induction cooktop with a bridge element. Of course you'd still need a griddle with no lip on the bottom. (And if yours has a flat bottom, say so cuz I'm gonna get one!)

I have a small square Lodge cast iron grill/griddle that works on the countertop induction hob. It has a small lip, maybe 1/4''. I don't use anything under the grill/griddle.