Megascenery Earth question

I was reading some positives and negatives about Megasceneryearth and I have a few questions for you all. I've read that at 3000 feet approximately or below everything is flat. Does this just mean buildings or would that include mountains. For example, if I am at the ground at a mountainous airport, does it look flat until I get in the air? I'm looking to get a better P3D mountainous western US environment and typically fly airliners so I was thinking Megasceneryearth might be a good choice. However, if on the ground and everything is flat, I wouldn't like that.

Second, if I have payware airports from Flightbeam for example, would Megascenery clash or wipe those out completely? What does it do to Orbx Vector and Open LC?

Last, I was looking at a Youtube video that showed some photoreal stuff in Xplane called Ortho4XP that looked incredible. Is there anything like that for P3D?

The elevations you have with your mesh will show properly and I will say that most quality mesh match the photo scenery so mountain side textures appear on the side of the mountain. However, yes the closer you are to the ground the more you notice that what you see at 3000+ ft looks more like wallpaper layed on the ground. So you won't see autogen treess and buildings unless the author has delicately placed them there. Airport buildings and custom buildings appear 3D.

If you place Megascenery lower on your scenery list priority then the payware airports will override the megascenery. It's really a hit and miss as to whether they match. More often than not they do not match.