Classic Hangar FW-190 work perfectly in P3Dv4. Or at least, I couldn't spot a single issue. (and that cockpit looks superb in VR).
But you are right about the FSX-only A2A aircrafts. Along with a few other FSX aircrafts that also use .GAU gauge files, these birds will not work in P3Dv4. They will display well, but there gauges or systems won't work at all.
You have probably listed all of the main differences between P3D 2.5 and 4.3.
There are a few other goodies though. The rain and snow now look much better, the autogen loads better too, and much more far away. In fact, the display of autogen can almost go to the horizon, provided your hardware can tolerate that (needs some CPU power, and a lot of video memory - the memory on the video card).
The various shadows also look much better in v4.3 than in 2.5, and that really changes a lot the rendering of some sceneries.
The main reason people jumped to P3Dv4 was the 64 bits. People got tired of experiencing OOMs each time they installed a few scenery addons. This problem is more or less gone in P3Dv4.
The sim still crashes to desktop from time to time, it's not perfect yet. But already much more comfortable than previous version.
If you are currently happy with your P3Dv2.5, you probably have no reasons to move to v4... yet. Addon makers are slowly leaving from the 32 bits sims, and will produce addons only for the 64 bit sims. It's like FS9 and FSX. At some point in not so distant future, if you want to enjoy the nicest addons, you'll have to jump forward.
