I find near 500 pretty farfetched, yeah. I've finished slightly higher than 480 as BLM while doing LB3 (as in not counting LB3's damage; otherwise only slight room for improvement or requiring one hell of a run proc-wise), but I also had i130 weapon and Selene.

I don't think SMN can win in T10 unless BLM gets victimized multiple times, in which situation a SMN is better than BLM.