Hey Mark, great to see you working on this again! I used Blitz3D for years, and it basically provided the bridge into the programming world for me. Much of my current knowledge of programming is still based around the Basic concepts I learned back then.
I've been working on an LLVM based compiler for Blitz2D, Blitz3D and BlitzPlus for about two months now (in total), and it's finally reached the point where it can turn most BlitzBasic code into an Abstract Syntax Tree, and even can now provide exact positions for warnings and errors.
I hope that I'll be able to use libSGD to fill in the gaps, as right now it doesn't provide anything that isn't just the Basic syntax itself.