I would recommend sending the KA circuit board to a repair service like FixYourBoard.com. $150-200 and you'll be back up and running with an oven you like. They get consistently good reviews by both consumers and appliance technicians.

I, like you have a 7 year old KA oven that works great, but I would probably not replace with a new one because there are other brands that people seem to like better now. Electrolux and Bosch are also the two I would be considering. It comes down to if you're willing to take a risk, or you just want tried-and true.

Electrolux has been using their current oven design since 2008. When it came out, it had some issues, including chipping porcelain and failing control boards. After a year or two in production they were able to successfully solve those problems, and they have continued to make small engineering changes since then. By now, the bugs have been worked out of the design. I have their slide in induction range in addition to the KA wall oven and the oven is great. The Elux wallovens are also very well priced for what they are.

Bosch's last generation of ovens had a great reputation also. The Benchmark, however, has only been for sale a few months so you aren't going to find much feedback at this point. They do offer some things Electrolux doesn't, including a color touchscreen, and side swing doors. Only you can decide whether those things are worth the risk of a new design and the extra cost.

If you send in the KA controller to FixYourBoard first, you don't really have anything to lose. Worst case scenario, they're unable to fix it, you don't have to pay them anything and you can just go buy a new oven like you were originally planning.