I think I know why so many ropeguides are getting damaged:
If used on a spar, they can't be retrieved safely unless a stub is used to run a throwline. I imagine many don't think about that before descending, and just let it flop off the spar onto hard standing.
Instead of a specific device, I use a couple of techniques that employ SRT as an adjustable FC on a spar.
The only time I'll use an adjustable FC is if I have to limb walk a broken tree (rare) - I'll set the rings (karabiners in my case) apart slightly to grip a spar. No need for something special here; I just employ my steel core flipline with auto prusik on one end and krab on the other.
This is in keeping with my working concept of a few items with efficient and safe versatility.