I'm thinking more along the lines of discarding Tileset editor and utilizing same code for both editing sprites and tilesets.
I can't help, but see mostly pros:
- You'd be able to expand animated tile functionality to include as many tiles as one needs, with animation methods for loop (now 1-2-3-4 in tileset editor) and ping-pong (now 1-2-3-4-3-2 in tileset editor).
- Sprite editor's code is more mature and you can do such things like move stuff around with mouse instead of entering values by hand
- Easier to maintain - you won't have to maintain two different codebases that essentially do similar thing.
From runtime part not much would have to change, except tile animations as support for more than 4 frames would have to be added.