I would pull the current cdfs (source, binary and manual page) and try again; there were fixes made up to and including March 25th.
RW media has been working flawlessly for me, though I think that for BD-RE I had to format rather than blank the media first. Make sure you've run dmaon first. Which flavour of DVD RW are you using, plus or minus? DVD+ certainly worked for me, but I didn't have much DVD- media (since it's inferior). I've just written about 15 dual-layer BD-Rs and that's worked fine except that, as now noted in cdfs(4), you don't want to finalize BD-Rs if you write more than one track to a BD-R.
