I'm really enjoying how Sally's vulnerability by being unable to roll, coupled with the new shooting mechanic alters the game's pace and dynamic, and it's a good fit for Sally as a character too. Your sprite work on Sally too, as always, is pretty much second to none.
I'd probably say it's balanced rather nicely at the moment - when firing, you can't jump and are left in the open, so you have to be considerate about when you're shooting - it lends to a more measured pace for the game. I also appreciate the amount of cooldown on the shots too so you can't just try rushing in Contra-style and attempting to spam your way through.
If I had to critique, I'd just say the spindash seems a bit hokey coming out of Sally, but I also can't think of any way that you'd be able to resolve that easily considering it's such a vital move for navigating many sections of the game, in particular the underwater parts of Aquatic. Perhaps some kind of grappling move could do it, or even modifications of some of the level designs to lessen the necessity of the move - I do of course realise though that these are not simple things to implement in a ROM hack and you still have to keep your scope realistic.
