Insurance on the Ninja 1000 is too high for the type of bike it is... but the INS CO's only seem to look at the cc's. 1043 is more than 998, so the Ninja 1000 costs more to insure than a ZX10r despite the fact that the 10r is a race bike and the N1K is a sport-tourer with about the same top end as the ZX6r. On top of that, the Z1000 costs about half as much to insure for essentially the EXACT SAME BIKE!!! Insurance aside, I love the Ninja 1000.
I traded my 2007 Z1000 for it back in May and haven't looked back. Yeah, she's heavy, but you forget that once you start rolling. There are two things this bike needs:
1) Exhaust - slip-ons at the least. I got the dual M4's for less than $500. They look good and sound good without being obnoxiously loud. But the reason you need to ditch the stock exhaust is that its so restrictive it causes unreal engine braking. If you let off the throttle, the bike wants to stop rolling instantly. With the slip-ons, you still have engine braking, but its not so severe and disruptive to your rhythm.
2) 190/55 rear tire. The manual says this is the stock size, but they ship them all with 190/50's. The 55 series makes a world of difference in the bikes geometry. Turn-in is noticeably quicker and confidence inspiring. They saved a few bucks by mounting 190/50's from the factory, but did a great disservice to the bikes handling. Break the bike in, and replace that rear ASAP.
There is no comparison to the 650. The Ninja 1000 has a better engine, better brakes, better suspension, and plenty of torque so you don't have to rev it to the moon to make her go. Nothing against the 650... it does what it was designed to do. But the Ninja 1000 is perfect for someone who wants something between a supersport and touring bike. I can rail all day in the twisties and not be sore in the wrists, neck, and back like my friends on their race replicas. The seat will suit some, but not others. I think the stock seat is plenty plush and it doesn't hurt my backside in the least. So its a keeper for me.