The one problem I see with this would be implementing it in tight spaces, caves, buildings etc. But I am sure it would not be too hard to figure out.

Imo, just adding the two class actions "ascend 10ft" and "descent 10ft" would be enough.
From what I have seen, the implementation of the fly spell is one of the things of patch 9 that people were most disappointed by. But at the same time, it seems very easy to fix (compared to other problems) smile

Good idea?