Glad to hear this hasn't stalled.
On the contrary. The racket7 repo is full of activity. In fact, I have many times wondered whether mflatt is a code producing robot. Just racket7 seems like more than a one-man job at times, with non-trivial patching of chez and lots and lots of new code.
I was just referring to going to Chez as the backend...happy it is moving along.