That 10 tooth may be useful for a shift kit, but I can't imagine it would be too much use without one...unless there is interest in pulling trees out by the roots.
With a 5:1 primary reduction and an 11-50 final drive, you already have almost 23:1 reduction- with the 10 tooth that would be 25:1. My Grubee Stage II has an overall reduction of just over 16:1, which is OK for my over 220# self, and while I am kicking around bumping the final drive up to 17:1, unless I was mountain climbing, I don't see an advantage to more reduction that that (and that's with a gearbox with probably significantly more drag than the belt...for now...hee, hee, hee).
However, as I said, to get that thing tuned to work with the shift kit, it may be necessary...and I sense that what Mr. Ghost0 is interested in.