I had 2 GSXR 750s and they were a lot of fun street and track. But damn the first time I rode my 1000 I was like "wtf I have been missing this whole time that I've been riding." For the street the 750 and the 1000 can't compare, I would not ride anything but a liter bike for the street given the choice. There's no drama when you open the throttle, the power just keeps coming and coming like it will never end. The 750 felt a bit like it was being abused when you went wide open throttle, the 1000 is rock solid and smoother at all speeds. It gives you a false sense of security and feels more like the bike is talking back to you "is all you got? open it more". In terms of weight, contrary to popular belief, I don't think my 1000 felt heavier than my last 750, the weight difference is not noticeable in street riding. The 1000 does eat up tires for breakfast though! For the track I plan on getting a 600 soon.
I don't know your riding experience level, but if you just started riding lately I would NOT recommend a 1000 for now.