Not commenting on luck - I know someone that has not gotten a 10-drop so far and has run it every day - but here's my heart totals for 6 chars over 20 days (120 boxes, a reasonable sample size for this sort of thing): 130, 90, 80, 80, 70, 70.
I might run it tomorrow on the "odd" totals (130, 70s) because if I crit I can get another costume to salvage. Anyways, that's 520 hearts totals. Subtract the 120 100% 1-per-box hearts and you 400 left from crits. 40 crits out of 120 boxes is a 33% crit chance, which is not too bad.