Stef: Great job with SF2 and now with SSF2.
About the graphics of the backgrounds, I think it should not be that difficult to improve, and also the tiles of the backgrounds and sprites are NOT compressed (Sf2ce neither does).
I use a program called yy-chr, which you can use to create tiles, but you can also load roms (not only Gen/Md) and you can easily find where are the graphics(if not compressed).
I took these images with yy-chr with color palettes that I extracted with Genskmod, I think everyone will recognize the graphics:
Attachment 9434
Attachment 9435
Attachment 9436