Brent,
first try was with some black plastic (?) which wore out fast. then switched to white nylon (hope that what it is, so more
??
) and never touched it again in 3.5 yrs. like i said just a few mm of wear.
cant really explain, but somehow the spring tension doesnt "feel" right, top run of the chain will get slack on over-run?
with a fixed block, the change in arm angle gets compensated by less "break" in the chain bottom run, so tension remains equal. i would do it fixed.....
then there's the question of sliding vs. roller.... less moving parts sounds better to me
TG