a buzz with medium tension strings sounds like an issue with your set-up
Thanks, Jack... set up's good, action's not too low: it's mostly that my right hand's getting stronger I think. Or I've gotta refine my approach... The buzz isn't a constant thing at all, just when I play much harder. Maybe I really don't need to; the guitar's got plenty of volume and even more though with the high-tension strings..I did ask him, and Steve told me high tension HBs are fine and to try the 200s, which he said he likes a lot as well. I'm getting medium/high for those.
I'll leave this set on a while yet but may experiment with individual string tensions, as you suggest. Wish the 815s came in medium/high!