to get this one rolling.
I have a KLR and last December got a scooter, not a Maxi just a 100 cc so I can't comment on the 400 you mention, how ever the ridding and experiences is night and day, how ever no wrong or better just different.
The thing I can say is that the KLR is a very high bike, a scooter will feel short, the feeling of been capable of going over any hole, rock and side walks,will go away as soon as you hit it! I no longer jump curbs, on the other hand wind protection is much better and with 400 windshield it will be even better, I no longer get cold legs.
The easy stores of the burgman is impressive, my little honda can't fit a full size M HJC helmet but it does hold a lot more than the KLR (obviously). Range? you will miss that on the KLR, on my little scooter I only get 100-120 miles per tank, but I do get 80-90 mpg so it is not bad.
I hope you get to ride one, since it is the only way that you can truly get to know a bike/scooter.
A motorcycle or scooter always turn a bad day into a great time!
KLR 650, Honda Beat scooter!!