I myself kicked the same thing around for around four months trying to decide on what to do. Since I'm not new to motorcycles/scooters I have always looked into each bike/scooter purchase as something I could sell if I wanted to move it on. After looking at the market and its poor resale valves of maxi scooter in general, I started looking for super nice used 650 Burgman that I felt I had to almost steal if I was going to buy one. Took me about six weeks to come up on a perfect 2007 with 3200 miles on it and in perfect condition. The retired doctor that was selling it was 72 yoa and said his riding days were over and just wanted it out of his garage. KBB was $4350 and I offered $3800 and he took the deal, we both were happy, him to see it go and me to purchase a like new scooter at a good price. Key here is look what you can sell one before you purchase one, I would rethink that before worrying about 15% fuel mileage, or if I could push it around, I would think about those thousands of dollars that you are going to loose over things that really don't matter. Burgman's have a good track record, that's what you need to look for, not be so negative on things that could happen.
John