Hi John,
I have the equivalent of your chafe gear protection on my hydraulic backstay adjuster at all times. The Sunbrella just compresses when the backstay adjusts.
The Sunbrella might help with a ding from an errant winch handle or the like, but my motivation was to keep the sun off that upper seal and dirt/grit from building up on the ram (and building up on that first seal when the ram retracted) that could increase wear on the seals.
Another “hack” is to always have a few pumps of pressure on the HB adjuster. This prevents the ram from “pumping” with changes in air pressure: even quite slight oscillations cause wear in the seals over time and repetition.
And lastly, my HBA’s default length, even with the turnbuckle fully tight, still left the mast poorly supported and the forestay poorly tightened for the jib when sailing. I had a pair of tangs made that would allow the HBA to be removed and the backstay tightened adequately by the turnbuckle. Not so important for a day-sailing boat, but very important for a widely wandering cruising boat (also helpful when the HBA is off the boat for servicing).
Not sure how much difference the above makes, but getting HBA’s rebuilt is expensive and not easy in many parts of the world.
My best, Dick Stevenson, s/v Alchemy