8.5 boot is fine for regular width boards. You won't notice it, trust me. I have a 10, ride a midwide Travis Rice at 258, and I don't notice anything different in edge to edge transitions from my old Optimistic, which was a 254 I believe. In fact, Libs are just so damn quick edge to edge, that Rice was one of the faster edge to edge boards I've ridden.
If I were you, I'd still demo the first day. Even if it's shorter than what you wanted, you'll feel the difference between the boards in the way they ride. Trust me, Ride boards with that low rise have a MUCH different feel than the C2BTX or Rocker-Camber of NS.
For me, center reverse feels just dialed (Lib, NS, Smokin). Others like more of a traditional camber feel. The Ride line will feel more like a traditional camber board (demoed a DH2).