Hi Steve,
All the adventure style bikes are big old lumps and because of this need a bit of manhandling at times. Most handle very well when set up properly, but at the end of the day it's never going to be as responsive as a GSXR. The rake is not as sharp, the tyres are a different shape and there's getting on for 600lb trying to push you in the opposite direction to where you want to be.
Go back to basics, set the suspension as directed in the manual, I'd definitely bin those tyres, they're going to be well past there best. Tyre pressure set to 36psi front 42psi back.
Scrub the tyres in and go and find yourself a nice run of twisties that you are very familiar with. Keep riding the same piece of road, take it steady and just play with the steering, actually consciously playing with the feel of counter steering and how the bike responds.
One thing that always strikes me with a lot of folks coming from sports bikes to the adventure style, is how shallow they keep their vision, keep that vision up and your eye on the vanishing point, it's a well known fact, the bike WILL go where your looking.
The GS is a decent enough handling bike, just has it's own idiosyncrasies. Well worth making the time and effort to gel with them. Smooth and planned is the secret to riding them quickly, try riding them like a sports bike and they'll let you know.