Reed,
It depends on the condition of the originals. If the originals are decent (not rusty, relatively undented/straight) and the plating is just thin, then it's always better to re-plate. Naturally, you need a good chrome shop to make the most of them (and I've seen lots of bad chrome work).
I understand the aftermarket bumpers are decent, but not as substantial, so I suspect they will not last as long.
Some people like to delete the bumper guards when they re-chrome, but from what I've seen, it can be difficult to conceal the holes left from the guards.