I also used to own an '81 or '82 Silverwing Interstate. I just don't understand why they don't make bikes like that anymore. Not just that one, but most of the great bikes they made back in the early 80s. Having ridden several maxi scooters lately, I was not impressed. A mid sized cruiser is just as comfortable, and easier to handle, especially in parking lots. And if you get one with a windshield and bags, you have wind protection and storage space. My Vulcan 750 seems to be a much better bike than the maxi scooters. Unfortunately they don't make them anymore, and mine is about worn out.
Valves can be a HUGE deal on a scooter. It's a 3 hour job on a little Honda PCX150. I got a Zuma 125 instead, because it is a 15 minute job. But if the Zuma turns out to be anything like my Vino 125, it has gone 25,000 miles with only one valve adjustment. But the thing is, you don't have to tear the whole scooter apart to check them. I consider this to be a design flaw (possibly done on purpose) on any scooter that requires it. More money for the dealer service department. I see no reason maxi scooters can't have hydraulic valves. Even the new Royal Enfields have hydraulic valves. They are not sport bikes. They already use the most inefficient drive system available (CVT)