I have a 1 liter. I have been riding for years. There is no need for anything bigger than a 600 - on the streets. Period. If you get on a track with a 600 and a 1000 that are both stock, you will log almost identical times - if you know how to ride. There is no one on this forum that can outgrow a modern 600 on the street. You are fooling yourself if you think you can.
It really doesn't matter how powerful the bike is. It's all about the rider's skill level. A good rider on a SV650 can easily leave a ok rider on a 1K on the track. Where the power of the 1 liter has an advantage is on the interstate and dragstrips. Concentrate on getting your riding skill level up, and it won't matter what you are on.
BTW - Learning throttle control while leaned over in a sharp turn in the mtns is MUCH easier on a 600 than on a 1 liter. The additional torque will make the tire break lose easier. Plus 1 liters are harder on the tires. Plan to spend more money on tires - they need increased grip.