Welcome to the world of DECISIONS DECISIONS DECISIONS..lol. I debated this VERY thought when I purchased my first and only bike. GSXR 600 750 or 1000. Knowing that I have self control and I'm now in my 30's, I used the "old fashioned" method of asking current owners of Gixxers. The overwhelming response was, "If I had the chance to buy a bike all over again, it would be the 1000." ..With that being said, I know SEVERAL 600 and 750 owners that are PERFECTLY CONTENT with their bikes and wouldn't consider a 1000. For me, I will swear up and down about my 1000. I hear a lot of owners saying, I wish I just had a little more power. Power comes with ease on the 1000. 600's or 750's make the perfect track bike in my opinion because they are nimble and very rider forgiving. On the 1000, its a little different. It's nimble on a level that is encourging but in the twisties, the 600's or 750's reign supreme. As for BRUTE power, it is hands down, no contest.. the 1000 is both feared and respected by most sportbike riders, whether it be a Suzuki GSXR 1000, Yamaha R1, Kawasaki ZX-10 or a Honda CBR 954RR/1000RR. I gather that you are NOT interested in a ZX-12 (1200cc) or Hayabusa (1300cc). That is a wise choice. Those are heavier bikes and they are not very nimble in the corners. Again, in my opinion, those would not be wise choices for your first bike. However, they are BIG BIKES and are very fast in the straights! It all boils down to this, what are YOU comfortable with? What are YOUR needs? What do YOU truly want to ride? ... Just my 2 cents.