How's vbcc? I've heard good things about it.
The 68k code quality is average overall. Vasm is the best 68k peephole optimizing assembler ever and the inline assembler used for many functions is fast but some of the statically linked vclib code and the backend need some attention. I've seen vbcc make optimizations I didn't think a compiler could do and then the next function will make me cry. It is getting better slowly though and there should be a new version out soon according to Frank Wille. There is major fixes in the vbcc compiler and vasm assembler that help with reliability. The beta is working much better on my 68060 Amiga.
SAS/C 6.58 generates pretty good code. You can even run it on your Mac or PC using AmiTools if cross-development is a must. It has basic C++ support, but no C99.
SAS/C generated 68k is average to above average really. It's about on par with GCC 3 and vbcc depending on the source. The last versions of GCC 2 were probably the best and may have reached good code generation quality, IMO.
VBCC is pretty ok, very simple to use and set up. It has C99 support but no C++. It's not meant for 68020+ only, the source code is available so you can compile it to run on an A1000 if you want, or any other computer and operating system for that matter.
Vbcc would be slow and require a lot of memory on a 68000. SAS/C or DICE may be better options. An fpga 68000 with plenty of memory and storage might be ok for small projects. An older compiler could be used for creation on a low end Amiga and then compiled with vbcc or GCC later if care is taken to avoid compiler specific code.
