I use ASE with REX texture. Quote often on a cloudy day I see very white clouds in the distance in front of (or through) nearby grey clouds, which looks odd and not realistic at ALL. It completely spoils the immersion. Does AS2012 also have this problem? Or did it fix it?

No its an FSX transparency bug, P3D devs are fixing it in future versions of P3d, it annoys the hell out of me also

Ok, thanks. Well, let's see what the next version of P3D will give us...!