Yes, all versions of WeiDU are compiled from the same source code (well, unless devSin has some diffs that haven't been merged in).
cmorgan: you don't need to COPY EVAL_BUFFER when you're compiling a BAF, COMPILE EVAL_BUFFER works both for BAF and D.
After checking the source, I found out that you can put arbitrary patches after an EXTEND_*, so you can use
EXTEND_TOP ~something.bcs~ ~my/mod/something.baf~
EVALUATE_BUFFER
as opposed to
EXTEND_TOP EVALUATE_BUFFER ~something.bcs~ ~my/mod/something.baf~