There are others on this forum who know much more than I do, but I am just about to buy an island hood myself. For starters, I would guess you want more than 300 CFM. Some things I have learned so far from shopping and from earlier threads:

1. From the places I have been shopping, Island hoods cost about $1,000 more than regular wall hoods. One way to help figure out what CFM you need is to go to a very good appliance place and have them calculate it for you when they give you an estimate. I did this just yesterday at ABT appliance just outside of Chicago. The other appliance store I looked at in Madison, WI wasn't able to do that.

2. It isn't just the CFM - You want to get a hood that is at least 6" wider than your range - I'm guessing you have a 30" range and will want a 36" hood. It is possible if you got a 40" hood you could get by with fewer CFM. (but of course a 40" hood costs more)

3. Are you going with an internal blower or external blower - Internal blowers are less expensive and may require slightly less CFM, but they are noisy. External blowers are quieter, and the CFM they require can be impacted by how far /high your roof is from your kitchen ceiling and whether the duct from the hood will go straight up and out, or with have any twists or turns. You will want additional CFMs for greater distances and twists or turns. The blower may need to be purchased separately. Make sure the price you get includes the blower!

4. What is your cooking style - Do you generate a lot of smoke from things like deep frying, high heat sauteeing/stir frying or grilling in a grill pan? Also, is your kitchen open to your living room or dining room so that smells and smoke carry over easily to other rooms. If you don't generate a lot of smoke and your kitchen isn't open to other rooms, you can get by with less CFM.

If you don't generate a lot of smoke, and your kitchen isn't open to other rooms, others in this forum might be able to advise you on whether you could get by with a "down draft" system which would be way less expensive, but according to threads I have read isn't nearly as efficient.

Also - Don't forget to consider if your hood provides a good overhead light, how easy it it to clean and if the filters can be put in the dishwasher.

I'm actually a chef and have just purchased the GE Cafe AG range (couldn't afford the Bluestar). I have much higher BTUs and do a lot of high heat cooking. My kitchen will be open to my living room and dining room so I am going with a Best by Broan IEX170SS 40" hood with a 1200 CFM external blower, but the price is staggering. After shopping around the best price I have gotten is $3,300.

Read the earlier threads is this forum on hoods - they're really great. I am so grateful for all the help and information I've gotten from this forum, the kitchen forum and the remodeling forum.

Best luck to you!

For an island hood you'll probably want extra CFMs. You should get at least 600 CFMs.

check out Kobe range hoods, probably best performance at best price.

With island hoods, the more the better. The hood really needs to stick out 3" on all sides of the cooktop, plus you need more CFM than if you had a wall hood. That 'rule-of-thumb' is really for wall hoods. You should figure on doubling it with an island setup.

As to why island hoods cost more, they are larger, have to be finished on all sides, have to provide lots of light, and generally only go in high-end kitchens, which allows them to jack the price up more.

Guadalupe (or anyone else who knows about KOBE hoods),

Do you have a KOBE island hood? Are you happy with it? Does it clean easily? How would it compare to a Best by Broan hood. I'm dying to know - I am just about to purchase my hood!