Force default skin. There are many objects from the default skin (in a different color of course) that it might look weird using other skins...
Next, offsets are not the same between difficulties; more specifically, the third offset. Even if it's not needed to place notes, you need to make them the same on all difficulties (think about the osu! "throbber").
Also, the hitvolume is not the same for all difficulties. I DID notice it, and there should be no problem with fixing.
[Lethal]
00:35:928 (6) - The second repeat arrow is hidden by the score explosion from (4,5).
Don't know if this is a serious issue, but I'd prefer it to be fixed instead of left there.
[Xtreme]
00:53:823 (1,2,3,4,5,6) - Not stacked properly.
That's it, I guess. Call me back and I'll proto-bubble it so it gets more attention.