To get back to the OP's original question. How do different bikes compare as to being "heavy and Cumbersome" I have owned bikes ranging from my Kymco 150 up to a 1200cc, 750# full dress touring bike. Size and weight is not always a good indicator of whether a bike will feel heavy. However, the question really needs to be asked in two different setting: At speed, and slow or stopped. There are many bikes which are heavy and hard to handle at very slow speeds which then "magically transform" to much lighter bikes at speed.
For example, my 1200cc, 750# Yamaha Venture was not only heavy but had a tall seat and high center of gravity. I'm 6-2 so the tall seat was not an issue but the bike was clumsy at very low speeds. Once moving however, it had light steering and was easier to flick into a curve than my 200# lighter FJ1100 sportbike. There are a lot of factors that good into how light or heavy a bike feels at speed. The main factors are: Handle bar width, front tire size and shape, rake, trail, center of gravity, and weight. My guess is that most Maxi Scoots with their fairly wide bars, low COG, and small tires will feel pretty light at speed.
Where most people have issues with larger and heavier bikes is at low speeds. If a bike is heavy, has a high COG and/or a tall seat (or wide seat), it will often be intimidating at low speeds or when stopped.
If you compare a Maxi scooter with a motorcycle of similar displacement, the scooter will typically be heavier but have a lower COG (except maybe for cruisers). Seat height on the other hand varies greatly by model.
I ride, Therefore I Am.