Andre: I know that BlitzMax is a big project for (essentially) single coder but if he's going to make Linux + Mac versios of it anyhow, then he have to solve most problems anyhow. Like moving to OpenGL and supporting PPC byte order thruout entire environment.
IMHO after those two hindrances are done rest of MOS port should be quite doable. Of course things like GUI are system dependant but I have been in assumption some of those details are going to be solved by Mos team anyhow (due other porting projects?).
Blitz 2000 could be nice but it is years behind in development, and making it to behave cleanly and producing PPC code is a *lot* work.