1) In the route description, you mention that 'the summit of Lower Catedral Spire is an easy scramble...' Did you mean Lower Cathedral Rock?
2) Can one scramble easily to Middle and/or Upper Cathedral Rock from the top of Gunsight?
Ooops. I'll correct #1 in the text. Yes, I meant "Rock" not "Spire"
2) Not easily, but it can be done at class 2 by either traversing below the rock faces on the west side of Middle Cathedral Spire or dropping down to the creek before heading south and then up to the other spires. There is a non-trivial amount of bushwhacking involved. Not the impenetrable type, just wear long pants and you'll be fine.