Well, I want BOTH eventually, but I meant just writing a program that booted from CD, even if that's all it did... like the DRAM cart test.
I noticed... "full" C++ support would make it easier to do certain things, like a Saturn version of scummvm. That would be possible with the 4MB cart as I've messed around with the N64 version, which runs in just 4MB of ram. That would also need CD support, as in reading files off the CD.
I think full CD support is more important than full C++ support. Get the former going first, THEN work on the latter. That's my feeling on the matter.