The thou has better brakes and suspension than the 650, not to mention THAT engine
It will not drop into corners like a 650 does, but once you have picked your line it feels totally planted.
A lot of people think that the SV1000 is the same as the 650 with a bit more power and a bit heavier - it is a totally different bike to the 650, apart from sharing a few panels/tank etc. As a result, riding the thou is very different to the 650 - you will need to re-calibrate your brain and throttle wrist when you open it up, otherwise you could end up in a lot of trouble
If/when you test one, do not try and compare it to the 650, just treat it as a big v-twin and enjoy it - if you get the chance to redline it in second and third I can highly recommend it (IIRC redline in second is about 93mph) - obviously that is assuming you will test it on private roads
