Various people I've asked about this have said they wouldn't use the .0
or .255 addresses themselves, though couldn't present any concrete info
about why not; my experience above would seem to suggest a reason not to
use them.
The .255 address is very likely to be a broadcast address from a
netblock of /24 or longer. I would suspect that folks are wary of accepting
packets from a broadcast address as that could easily be a smurf.
The .0 address was used as a broadcast address long ago and then
was deprecated, so the same rationale probably applies.
Tony
