I'm a "big boned" lad and already notice the wallow in bends
That's the swingarm twisting! It was one of the first things I noticed coming from a braced swingarm on a ZX9R. It's one of the reasons Gen 1s are so forgiving on bumpy roads though. There's a lot of give from the long forks, ex ThunderAce swingarm and steel frame so it just clatters over bumps. Ideal for this country! And it'll still let you run in the fast group on a track day.
The big problem for big lads like me on Fazers is the rear shock is undersprung so it sits down at the back and makes the steering lazy. Then at 30,000 miles the damping goes off and you start boinging about all over the place. If it hasn't lost the damping, just whack the preload up until you can get hold of an R6 shock, or get 25 quids worth of dogbones to jack the rear up a bit.
Personally, I didn't replace the shock until it was well and truly gone, but it has to be said, propping the rear up with an Ohlins was like buying a new bike. But it would, since the old shock was utterly knackered.