@dwcco :
My short answer: I would pass on the 650.
Long answer:
1) I test-rode the 650 some years back -- when it was still in production -- at my local BMW dealership. I was hanging around with a friend, who was having some service done on his RT, and some salesperson suggested I give it a whirl, unsupervised, on a route of my choosing.
I found the 650 to be quite tall in the saddle, as if it were made for the giants who ride a GS and some other Beemers.
Of note: A) I'm 5'8", with a 29" inseam; B) I was quite used to 650-size scooters, because, at different times, I owned two Burgman 650s for a total of 11 years. (In addition to those, I've owned a couple of 900-lb. baggers -- a Valkyrie Interstate and a Victory Cross Country Tour, along with an R850R, and now a C 400 GT and a Royal Enfield Meteor 350.)
Unless you have very long legs, at your 5'6", and your being middle-aged and sort of new to street bikes, I think the 650 might be a little unwieldy for you. (And as a former MSF RiderCoach myself, I've seen a lot of new riders stop with the front wheel at weird angles and drop bikes, that sort of thing.)
2) I think a middle-aged BMW might be an expensive proposition.
I know a lot of folks opine that BMW service is expensive, but owning both a BMW and a dirt-cheap Royal Enfield (both 2023 models), I disagree with that. Routine service has very similar costs on both of those (and I know, because at 78 now, a few years ago I stopped doing all maintenance myself, and instead farm it out to the respective dealerships).
However, when it comes to something breaking on the bikes -- I'm primarily talking engine or drive-train issues -- the Beemer would be very expensive to repair.
Hence, I personally would be reluctant to own one without its being under warranty. (In fact, my '22 C 400 GT was replaced, in '23, with a brand new '23 scoot, as a result of an engine problem. BMW picked up the tab.)
3) The C 400 GT does everything I want of a bike: handles absolutely superbly (with a lean angle of about 41°); gets up to a GPS-verified 89 or 90mph (although BMW lists the '25 model as having a top speed of 80, vs. their listed 86 for earlier models, but it is still highway capable); doesn't vibrate to the extent that I notice it; looks sharp; and is much lighter and lower than the 650.
If the cost of a new C 400 GT is out of the question, then I might look for a late-model Burgman 400, or an XMax 300, or ditch the scooter concept and look at any number of, say, Royal Enfields (the Hunter is very light and low, and lists for about $4,200, for instance, although the 350 REs are not all-day highway capable, but the 650s certainly are).
That's my take, but I'll likely be out-voted big time by the more prevalent 650 owners on this forum. Good luck on whatever you decide.
Edit Addition: If money is not much of an object, and you really want a maxi-scooter, you might be interested in the Kymco AK550. Twin cylinder, frame-mounted, engine, just like the former Beemer and Suzuki 650s, and lighter than both of those.
