Yes, the mini is the only official release it got but you could argue that it's not authentic since it doesn't run on the hardware its designed for.
I think Star Fox 2 seems to run faster than the original Star Fox. All Super-FX games are kind of stiff, but they are generally designed with that in mind. Overclocking the FX chip generally makes the games too easy, because the SNES clock still runs at normal speed, which means things like timers are still slow while the player becomes fast. You can make super fast runs in Stunt Race FX for example if you overclock, and you never have to worry about time running out.