After a few runs, I loved Final Rush. Just imagine if you could effortlessly jump between rails like in every 3D Sonic game after Adventure 2. Its sad I don't even expect that fix.
Well... technically modders could probably make switching grinds easier, though, I really doubt that would be any sort of priority anyway. The way switching grinds still works in SA2, it just takes a bit of skill and knowing when you should switch.
I, personally, don't like the tacked on feeling rails serve now in the Sonic series, especially since you can't fall off of them now. In SA2, there was a place for them where it made sense, and while there were two whole levels dedicated to grinding or had a lot of it, that was part of the challenge in a sense. Sky Rail wouldn't be as memorable, IMO, if you could effortlessly switch rails (music aside... and visuals). Granted, Sky Rail would probably benefit from it fun-wise, it just would suck all the challenge out of that level.