The problems I have had are strictly to do with NPC-NPC animations. I do not want to restrict PC - NPC animations as that is one of the main benefits of OStim. OStim currently has lots of problems with NPC-NPC animation sets. You cannot use sequences with NPC - NPC animations even if you specify the exact sequence. If you use the Tags="lesbian" argument to retrieve animations, you get exactly one animation for NPC-NPC requests even those both (or all in FFF animaitons) are female. Specifying a lot of action tags as in AnyActionType = "rubbingclitoris,lickingvagina,femalemasturbation,lickingnipples", you get back a lot of animations even though these are all tagged "Lesbian".
In other words, I have no problems or issues with PC-NPC animations. Only with NPC-NPC or just NPC solo animaitons, I have a lot of these to that I will have to port and it would be a lot easier if these all worked well. Never had any of these issues with Sexlab or Flowergirls. I have already experimented a month of 8 hour days with OStim and do not yet have a solid road map in my head as to how to proceed with an OStim port.
If I had the time, I'd get into the OStim source and see if I couldn't fix this stuff. I have written millions of lines of C and C++ code, but I am loathe to dig into a large codebase that someone else wrote again.