SRAM Expansion Patch (32Kb)

I have read somewhere that this space reads/writes slower than the onboard RAM in 7E/7F. Is that true, and would it much matter?

I've never read this but I have not looked for this info either. Where did you read this? I guess it wouldn't change anything if you don't read write often per frame to it, depending of the use some tests would be needed. BTW, FF6-G a japanese hack use the same method, and it is used in various places.