Remember that the smaller displacement bikes are lighter and can be tossed around like a hooker on her prom night. Nothing wrong with the sub 600 series bikes as fun toys! In fact because you can wring their necks without breaking the sound barrier, I'd say they're possibly MORE fun than bigger bikes.
That's one of the things I keep telling my self. Going from my current Nighthawk to the Ninja 300 I would drop almost 60lbs of weight. Even from a modern SV650 it would be over 40lbs. In my ideal world I would have a 300 and a supersport. One for just cruising around and one for when I want to got FAST. I can't have 2 bikes so getting an SV650 is a good middle ground and most likely where I will end up.