I always run my S2r on super unleaded, either Tesco momentum or V power for no other reason than the alleged cleaning properties of some of the higher octane stuff.
The Mito demands a rating of at least 98 so that also gets the good stuff.
The child's Skyteam Ace gets run on super unleaded as well but with about 3hp it needs all the help it can get
And the amount we use, the cost is minimal so why not?