Grunker
RPG Codex Ghost
Even though your build didn't work out the way you planned, I love that there are so many possibilities to experiment with and think about even after the game's been out this long.In either case - I was wrong!
Honestly the hit to the build isn't that bad if it worked as intended - the most important thing is the BAB and losing the 0.5 multiplier. As well, this insane bonus only comes at Mythic Rank 7, so it won't be relevant for most of the campaign anyway. But if Yosharian is intending to use this on the more demanding islands, it will probably affect him more.
And it certainly sucks if some of the naturals keep the 0.5 multiplier on damage, because that's a really big hit.