due to issues concerning the developer that we were using for the PC-side executable.
So what part of a compiler isn't PC-side?

Anyways, even if they released a new compiler tomorrow (which they clearly are not) you'd still have to port your code to a new compiler (would you base a commercial product on version 1.0.0.0 of a compiler?) and there are already several mature options , one you've already mentioned and Proton24 (which I see supports several 256k Flash PIC24 devices). It looks like you've got to bite the bullet one way or another.

As I said before, fascinated to hear your progress.

George