I've always thought these shuttle buses have some really good potential! I like windows so it appeals to me, a lot of vanners do not like windows though, mostly privacy and insulation concerns which are more difficult to deal with.
Most states will require a CDL to drive anything with over 15 passenger seats (I believe that is a Federal standard), in that case you need to remove seats & change registration regarding number of passenger seats before you could legally drive it. The other snag would be insurance, depends on the carrier/broker how easy it is to add a former commercial vehicle to a personal policy, a quick call with the VIN to some agents would be the quickest way to find out.
There's of course a mileage, maneuverability and parking penalty vs. a smaller vehicle, but everyone will weigh those traits differently based on what they want. The Triton V8s in the vans are prone to spark plug issues that certainly adds to the long term maintenance costs and hassles, but there are still many more of them rolling around than any other van currently in America despite that flaw. Just one more thing to consider. That's all that stands out to me at the moment!