It depends the systems that are implemented. The TBM uses some custom screens, driven by some pretty intense code, for the G1000, and X-Plane has trouble replaying stuff like that. Default will ALWAYS replay, because it uses some xlua and generics. It's similar to the Saab that I made. Sounds won't work in replay mode (custom sound engine that X-Plane can't read in replay) as well as systems.
I'm not sure if they also work, but I'm guessing the glass cockpit airliners would have trouble displaying everything in replay, as well...due to the nature of the displays being rendered.