Digital BW, The Print

This may border on OT, but here goes...

I'm looking for suggestions on testing a digital camera's BW mode against 
its color mode for BW output.  The question is: how does shooting in BW 
mode compare to shooting in color & converting later?  Converting later has 
the advantage of applying contrast filters after the fact.  Would BW mode 
be likely to offer advantages in, say, sharpness or dynamic range?  How 
would one test that?  In particular, what sort of test target would be best 
for sharpness?  Maybe something with saturated reds, greens & blues 
bordering each other to look for fringing.

The camera in question is a Canon G2.  It locks some functions in 'auto' 
for BW mode -- e.g., exposure is program mode only.  At least the ISO 
setting hold when switching to BW.  Low compression .jpg is the top quality 
save option in BW where Color includes a RAW ccd output losslessly 
compressed (about 2x the BW .jpg size).

Regards,
Bob G