GR_FOV is field of view. It is an OpenGL command which controls the 'zoom', and is how the sniper bind worked. I got AJ to enforce it to the default in netplay, because it's gay.
Mouse control is better than keyboard only, no question. My question is: Why aren't you using it? It's not like it's a bind or some secret. By default, mouse control is on. If you move the mouse, Sonic will turn, albeit slowly, something that can easily be changed to your taste. It will probably take a little getting used to, but it gives you a LOT more control over your character's turning.
I can and occasionally do play with keyboard only, but I don't like to. It's like playing Mario 64 with a keyboard. I can do it, but you lose a LOT of precision without the analog stick for directional control. In splitscreen, I don't have a choice; online, I do. Hence, you only see me play with mouse and keyboard, but just to prove that it's possible, I did beat Special Stage 7 by over 50 seconds with a keyboard last demo to shut someone up.
OpenGL mode is a technical advantage, but no more of an advantage than playing at 1280x960 is. If I can win at 320x200 software, OGL just makes it look a lot prettier, and lets me shoot the idiot you hit the vertical spring right after me ^_~
There is no way to make it completely fair to all players. My objective is to make it as fair as possible, and binds can be abused very severely. Unlike mouse control and OGL, which give subtle advantages, binds give a very drastic advantage to the person who is using them. Hence, it needs to be fixed somehow.