Not familiar with the reels but if they are metal on the wear points (arbor, arbor bushing, and pawl) they should last for many years. As with all composites, the elastomers in the resin will eventually leach out and they will embrittle, but we are talking decades here so not to worry. After all, they make rods out of graphite composites.

There may be some who will claim they are too light for "balance" but that is a personal preference thing and has no merit in physics.

I happen to be one of those "reel" guys who like their hardware. But that is just me. There is no practical reason for it. I just like the sound and feel of a precision machined piece of alloy.

Bob