I haven't tried the Sportsman version so can't really comment other than to say Pat always comes out with top notch stuff. I'm still running a Manic Mechanic version from some years back and had an extra sprocket for it, so when I needed another clam shell I got another to fit the sprocket I already had. Both have worked fine without a problem. And now I'm using either moped hubs which already have an engine side sprocket or belt drive which doesn't need a sprocket since it uses a sheave pulley. And as an aside, I have also used the kit rag joints which work OK for a normal build (not racing motor) if installed with great care. The clam shell is a more sure thing and simpler to do, plus gives you some lateral adjustment... worth the expense, in my opinion.
SB