I can tell you that Version 3.1 is very very stable and works very well with Estonia Migration tool. I fly the Level-D 767 when ever I can. The only problem with version 3 is that there are software restrictions built into FTX Central. With that, one can NOT run scenery software purchased from Capt. Jack. Only "Flightsim Store" FTX software with a serial number is allowed to run (Orbx products). If you load your "flightsim store" store scenry from FTX and also try to load FTX software bought from Capt. Jack then the entire Orbx folder will be erased.
So....... Version 3 of Prepar3D? Fantastic and Stable. But be prepared to buy FTX scenry from "the flightsim store" only to get the best possible terrain views.