Just thought I'd share my experiences, both for range help and kitchen design. We purchased our Jenn-air slide in downdraft gas range 2 years ago for around $2000. It looks great, the burners perform wonderfully, and it has a beautiful black glass top (well, intially beautiful, turns out it is difficult to keep clean and always looks streaky and smeary no matter what you do).
Unfortunately that glass top cracked the first time I used it. It was replaced under warranty, and the day after the replacement....cracked again. I have not even bothered to replace it this time, as this is a much smaller crack, and I really do not want to risk getting a bigger crack, and go through the hassle of having to replace it again the next day.
A few months after that, the touchpad controls stopped working and had to be replaced. Today, the touchpad controls stopped working again. I have 50 people coming to my house on Saturday for a party and I am waiting around for the service tech right now to come out and check it...they won't just order the part, even though it failed once, they have to come out, take it apart, "make sure it's not a loose wire or something", and then order the part and come back again...meaning, probably no oven or stove this week.
Just a heads up to anyone who is looking to buy a home or remodel a kitchen...stay away from a downdraft range in the island...a cooktop is ok, I am referring to a combined range/cooktop slide-in unit. Your choices for this unit are very limited, and pretty much all bad. Be aware that Jenn-air, Whirlpool, Amana, Maytag, Kitchenaid and several other brands are not what they used to be...they are all part of Whirlpool and all the same poor quality products now. We learned this the hard way, although unfortunately for us, the way our kitchen is configured, we don't really have many other options.
In defense of Jenn-Air, I had a glass-top with downdraft installed when my house was built over 30 years ago. Although I never stopped complaining about how godawful-long it took for the cooktop to heat up and cool down, it was always a breeze to clean, it never scratched, and the downdraft (my only venting option) worked a gazillion times better than the new Dacor downdraft exhaust I had installed with a new Dacor gas cooktop a couple of years ago. But that was then, and this is now, and from everything I've heard and read about Jenn-Air, they just don't make 'em like they used to.