Product review (4 stars): On the Knob Issue
Disclosure:  I don't own the range yet, but read the reviews with the comments about the knobs and because I was interested in purchasing I contacted GE to see what they had to say about the issue, especially because the reviews were older which named the knob heating/melting issue.  GE Responded below:

"Thank you for contacting us. We appreciate your interest in our GE Cafe free standing gas double oven with convection. This is a great range, I can see why you would like it. I will be happy to assist you.

We found that, in many cases, when broiling the door was being left open. This is no longer necessary. There were also cases where the racks had been placed in the oven backwards (unbeknownst to the consumer), which caused the gasket not to seal properly causing the knobs to heat up.  However, the knobs have been changed to a die cast metal and the collars are made of a heavy duty plastic. Additionally, there was a change made to the gasket.  The knobs as well as the collars have been tested extensively and will not melt. This range vents from the rear. At this time there are no ranges available in this line that have 100% stainless steel knobs or plastic collars.