Gary
I fly a Vixen with 912UL. Bought it in CA in late 2009 with just over 100 hrs. I installed a IVO IFA prop and now can get 117 MPH if I want to burn some fuel. It now has 450 hours, burn regular unleaded mogas and normally cruise at just over 100. I get off the ground quicker than most GA`s with a pretty comfortable ride. It has been across the Rockies at 11,000 feet plus a few times.
I don`t honestly think you need a 912S unless you are flying out of a lot of short unimproved strips. The UL is cheaper and easier to maintain in my opinion. Of course, my opinion is only worth what it cost.
Cheers
Don