I have never done high pulls, but they seem like a great trap exercise and a great alternative to shrugs for trap “isolation.” It seems that they might make a good addition to HST, but what about the high reps (10-15)? Would high pulls work very well for this many reps, with such a light weight? Any other ideas for trap work in HST (other than shrugs)?
I did a cycle with no isolation work for traps, and just relied on the deadlifts and upright rows for trap growth. It worked.
Additionally, you could try overhead shrugs, jump shrugs, etc. Also, Alessi's low trap raises would probably work well.
Hope this helps.