Noggy, you shouldn't let your experience of the gen 2 colour your opinions on bigger bikes too much. You got unlucky with a bike that wasn't set up well, and you had neither the time nor money to sort it properly. But I am certain that given those, it could have been set up more to your liking.
It's not a question of whether smaller and lighter is better. Such a bike might be more nimble in the tight stuff, but in the UK at least, that same tight stuff also tends to be bumpier and less well maintained....perhaps a heavier bike soaks up those bumps better? Or maybe a dirt bike or supermoto is better for that? Or perhaps we all need 3 or 4 bikes?
Roads vary. The bike you go out on, on any given day, doesn't. Looking for perfection in one bike that rides those roads is futile in my opinion. As long as overall you enjoy riding whatever you have, then that's good enough. The gen 1 has it's failings, but the reason so many of us stick with them is what I said before - they do everything to a reasonably competent level, and some things bloody well. The 600 is the same in that regard, as you know.