I have read that lots of people have used the firmware hack. I have even read the someone sent in a hacked camera to Canon for service. Apparently they don't seem to care. They either don't bother with the firmware or they just reset it to the Rebel defalt...in which case you just re hack it again.
If I had a D-Rebel, I'm not sure I would hack it without seeing someone do it to theirs first...but word on the street is that it's fairly safe.