CFM doesn't really mean the same thing for recirculating. If you look at the specs for many hoods that can be used either way, they list a number for external venting and usually just a blank for recirculation.

You won't find any hood that lists 400 cfm for recirculating, for instance.

Thanks for that info. It turns out the Ventahood is too much for my blood. The hood enclosure is about $1000, but you have to buy the "guts" separately, which would bring it closer to $2000+. I'm just not willing to go that high!

Yeah, sorry, I realize I wasn't clear about that in your other thread. Well, if not that one, I don't think there's much difference among the rest of the pack, so just choose a style you like.

Look at the Miele 3490 built in ventilation. It has a recirculating option with charcoal filters.