Where the sceneries join I have missing tiles some if I fly over them appear like magic and then disappear.
I have used both FSET and AeroScenery, I find AeroScenery much simpler to use (less effort required) and the whole process is a lot faster (for me anyway)
Similar to you, I used to have tiles appear like magic, this is no longer the case. NOTE: I reduced the visibility a little (seems to have a positive effect)
There is no real learning curve using AeroScenery, nickhod has made the tool as simple as can be and is continually improving it.
Keep it up, you will not regret using these tools and AFS2.