ORBX (say, mostly Tony Wroblewsky) has done a great work on True Earth. I own all three XP parts and enjoy exploring them. And this, while I've never been an X-plane fan. I bought all their UK XP airports (using the cross-rebate), too.
Unfortunately, ORBX failed with the Prepar3d counterpart. I got it to run more or less after playing with settings, installing the Service Pack, resetting my Nvidia settings and stuff. It now runs so-so, however, I just can't make fun of using it. I rather got the impression, while the XP version has been a work of art, the P3D version just had to be done, as the user are (or should I say were?) there.
As a result, I observe flocks of folks switching either completely or in parallel from either FSX or P3D to XP right now. ORBX just isn't one minor airport maker but certainly a (perhaps too influential those days) factor in the game. Morever, JV and his subordinates make no secret of the fact he completely fell in love with X-Plane.
I put a question on their forum why they don't team up with LM to release a similar P3D/ORBX TE demo. The answer by that Aimee Sanjari was P3D:XP is still 70:30 among their users, thus there's no need. But have a look on new releases among all makes, which are 2:1 from XP:P3D, at least. And that's not only conversions but mostly new developments.
I can't say I am really happy about that, having invested thousands of $$$ into P3D over the years, but what can I do. Unfortunately, P3D indeed has been plagued by a host of inherited shortomings LM obviously never are going to cure. I made a list of serious issues of the terrain engine alone on AVSIM a few months ago, which included 7 items.
Kind regards, Michael