Hi,
Studio One has built in Mackie HUI compatibility (an pre-built External Device that installs with it) in all versions so it should work with any version.
If you have access to an HUI the best thing to do is to try it with Studio One 2 and maybe also try it with the Studio One 3 demo see if it fits your needs in general and or if you notice any discernible difference in support between those two versions.