Product review (4 stars): Good downdraft
Had this installed as part of a kitchen remodel.  This was expensive, but the stainless hoods were all far more, so we decided to go with this and vent the steam/smoke/heat through the crawl space under the kitchen.  As stated by the other reviewer, this vents best on pots on the back burners right next to the vent.  Even with fan on full power, it does only a good, not great, job at venting the 2 front burners, which are the ones we use the most.  I cannot comment if this is better or worse than other downdraft vents, but I would not be surprised if no downdrafts can vent the front burners any better.

CONS: Loud on full power, vent can only go up to the full 15" and not part way and u cannot turn fan off and keep vent up.  I just assumed that this could go up part way, but it cannot.  It would be nice when using low pots to just raise the vent half way.  Similarly, there are times that i would like to turn the fan off, but keep the vent up for use in 10 or 15 minutes, again, this cannot do this.  It would seem that these would be easy engineering changes and am disappointed that such an expensive one would not offer a little more flexibility.