I will say.... nothing lost, but my first instance of an existing project that had both Superior and EZD, after BOTH Toontrack items were all updated and the midi packs, etc.. I lost playback on ALL the other VSTi in that project. I was able to just create another VSTi instrument track, copy the MIDI over and set the VSTi up like the one not playing.... and back to square one. IF I would have had a pile of sessions like this, this might be trouble, but it was my first X3, experiment session, with a pile of stuff, but NOT a serious session. I guess all my old projects which were actually in 7PE might do the same, but they're history at this point anyway. Possibly a good reason not to upgrade mid-project??
Other than the Superior NY kits... I'm finding EXD2 to really be something good. Makes me hesitate buying SDX NYvol3...and a bunch of other expansions. EZD2 really lets you dial in more than you'd initially think.