Oh well. I guess I can just snag one and see for myself. I kinda want an archer (other than Aela, who I cant stand).
I know J'zargo scales up to level 81 if I recall. I too was wanting an Archer, and since I always play an Argonian, Deerkethus was the perfect match. He's a very good archer. I removed his default weapon (pick axe) and gave him an ebony bow/arrows and bam, bad ass archer companion.
Also worth noting is he doesn't talk much, (except when approaching a cave/enemies in a cave/epic area like everyone else does) in fact the only idle talk he does is he briefly hums a tune to himself, so much less annoying than say Mjoll who's like "Durr me and Aerin did this one thing one time," or "I learned to use a sword from some random face ISN'T THAT CRAZY?"