SA sent me an assembled inner... it helped about 80%. Before the hub was actually jumping in & out of gear, now when it does a "bad" shift it stays in the correct gear, just with a lot of clunks and clanks. Shifting back and forth a few times will find a smooth engagement.
I too like the whole kickback shifting thing. The S2C could be made a whole lot better, but I'm keeping it.

One odd thing about the replacement part... there's a race with ball bearings in it on the cog side, held in by everything that goes on after it. That race was completely tweaked and bent, and loose balls were in the plastic package. I ended up disassembling the new assembly and disassembling my old guts and swapping that race.