Our team does
something similar to tension our drive chains with black delrin, and we haven't experienced much wear. Our only problems have been the bolts loosening and the cams rotating away from the chain (loctite would probably fix this) or the mounting bracket being insufficiently supported. You also have to make sure the cam has enough play to take out more slack when the chain stretches (we had to drill a second hole in one of ours at competition for this very reason).
Btw, I like how you cut a slot for the chain in the tensioner material to keep it in line. We'll have to consider something like that for future drive trains. How did you machine it with the guide grooves?