I have a branch that will soon allow using either Boehm or MPS on the various backends. That'll probably be the case for the LLVM backend as well.
Part of the reason that I'm doing that is to help gather some performance data on the MPS. (I'm actually doing that Dylan runtime work under contract.)
I actually met prom yesterday and he showed me that there are much more information on MPS know. I already read threw most of the documentation and I'm very interested to maybe use it.
I don't yet fully understand the license and what it means, I will probably join IRC in the next days and dig for some more info on MPS.
Great that you get payed to work on this.