No doubt, Ryan is spot on. ORBX added a third sim to their scenery efforts and it was AeroFlyFS2, not xPlane....that should tell you a lot. P3Dv4 still has a ways to go, but now 64 bit, they have the resources that apparently XP did not. Now FS2 doesn't fly where I want to, so that's not an option. RTMM has created a masterful library that would keep any Bush Pilot happy for a lifetime. There is even a VA dedicated to ORBX and RTMM....I know, shameless plug.....but if you fly in the bush, you won't have a huge hanger of airplanes...most operators have one or two in a lifetime, but where you fly is endless.....and RTMM along with ORBX delivers just that. I just don't think there is enough interest in XP or for the moment FS2 to consider an addition.....I am sure you like xp, but IMHO that's the way it is.
Henry