I just got rid of my Jenn Air downdraft cook top, I am so happy with my new cook top and range hood. Down draft ranges and cook tops are useless. Do not buy one you'll be frustrated, it will drive you mad, your quality of life will take an immediate hit. They take forever to cook anything. The problem is that the heat is pulled away from the pot. I replaced my downdraft with a normal cook top and a Broan Elite 661 hood, (460 cfm.), the difference in performance is day and night. I can now boil water in 4 minutes instead of 15 minutes.
There is also a significant fire hazard with a down draft. I had the oil in the pan, and it got to hot (it is amazing to get anything hot on a downdraft but in the case I succeeded). The oil vapors were pulled past the flame and ignited hence FIRE, FLAMING OIL. A quick placement of a lid to cover the pan saved the day.
The downdraft range or cook top is the least Green appliance in the world. It is sucking the heat away from the pot causing the use of more fuel to heat, and more electricity to run the heat removal fan which all downdrafts have to frustrate you. The guy who invented the downdraft cook top has a vested interest in melting the North Pole. That is where the heating is going, it is not going toward frying yours eggs.