well, seems I missed it ... I'm still with old good alexis 20mhs per gtx1080ti
On the 1080ti, I get 20MHASH with 80% tdp and the blake2s sp-mod #2 does 7000MhASH
Thats 350 times the speed of x17.
live prices from zpool
1GHASH x17 0.074btc / Ghash
1GHASH blake2s(sp-mod) 0.00019677btc GHASH
(So x17 has 376 times the payout of blake2s. Amost the same)
with your big farm it is very stupid to mine on pool ... fast block time, heavy load and bad configuration produce a lot of orphans and missed blocks on pool.