I'm a bit of a novice at full fidelity airplanes, and have found the FMC a wonderful learning experience. I did have a few CTDs when trying to input FPLs into the FMC at first and thought it may be my lack of knowledge ... but now I've read this thread, maybe not. I have eventually flown KSEA to KSFO a couple of times now, with only the severe pitching after a while to contend with, fully under the command of the FMC. I have not tried to change arrival details yet though, or anything else enroute so I have that experience to look forward to.

With regard to the severe pitching it looks like it may be set off by active thermals generated by FSX ... perhaps .. maybe.