I can't comment on the quality of the aftermarket tramps (since I almost exclusively race, I have to be class legal = Hobie Tramps).

The heat welded OEM tramps are damn near bullet-proof, though. Mine's 7 years old and looks almost new, except for the brass grommets have turned brown. Then again, I sail in fresh water for the most part and the boat is garaged year-round.

It won't hurt to replace the lacing on a 24 year-old tramp.