The home I just moved out of had the Jenn-Air downdraft electric cooktop that was in the house when we purchased it.  I used it for over 16 years and loved the downdraft vent.  It was also handy when we failed to open the fireplace flue and smoked up the house without realizing it.  I turned the Jenn-Air vent on and it cleared the air in no time at all.  It was good when you needed to get odors out from painting, cooking, fireplace smell, etc.  Loved it!  We did change the cooking cartridge out to the smooth top which also gave me 2 more burners but could put the grill back in if needed it.  That allowed me more cooking options than with the 2 burners and a grill.  Nothing better than the Jenn-Air as far as I am concerned.  The only drawback is that you do need to plan for it if your cooktop is on an island or away from an outside wall since it does need that outside access for the vent. Would need to check with an installation man to see if it could be added to existing kitchen.