i had one of my KDW's patched twice (at the same time - two nails), though i never felt totally comfortable with it afterwards. of course, that had more to do w/ them being bald than anything else.
just make sure it's patched from the inside, not "plugged" per se (if i have the terminology right). i might lean toward replacing it if you raced a lot (autocross/track events) or ran at really high speeds a lot, but for most normal driving, my humble opinion says you'd be fine.
hth...
