I went from a 650 to a 1000 last year after 4 years on the 650.
The 1000 does everything that the 650 did, but quicker/smoother/better.
The acceleration is the biggest difference - the 650 needed to be worked a bit to get the best out of it, however the 1000 will just take off in any gear. If you do decide to knock down one or two gears on the 1000 then it sends your eyeballs to the back of your head.
It does not seem quite as 'chuckable' as the 650 was, but it is a bigger/heavier bike - the 180 section rear tyre probably accounts for a big part of that too.
Insurance is not too bad - I am 35, 4 years NCB, bike is garaged but not alarmed, 5000 miles per year - best quote was £250.
Prices for mods - depends what you go for - cans will be twice the price of a 650
, fairing lowers are about £400
See here for lots more info:-
http://www.sv1000.zyns.com/