[zbentley]

I've found that tuning some of the SMB options ("man nsmb.conf") has dramatically increased my recent Macs' SMB network throughput and the responsiveness of finder in huge/deep shared directory hierarchies (due to caching).

I don't know if any of those apply to using OSX as an SMB drive host, but they might.

None of this should be taken as disagreement with your post; just ideas for improvements if you find yourself thus frustrated again.