To be honest about the PS1 changes, it should be a stage that actively changes. not just asthetically, but as a stage as well. If it doesn't, it's just a glorified version of a different stage pretty much aside from that one phase.
The ice stage should retain the sliding. Wavedashing becomes much more effective, and I'm sure Dacus would be even more advantageous there. Could be great for some shenanigans.
Personally, I'd rather the ice stage have a platform or two as well but you can't have everything.
If I read it correctly, the fire stage is replaced by only one of the ones he created.
That's tragic.
I think if the fire stage was redone a little, and both the ice and electric stages were added it would be a much more interesting stage.