Some interesting thoughts. Personally I reckon you should buy what you want. Regardless of our opinions as you are going to have to own it for X years.
My First bike was a 400 four Honda, and my second was a 1000cc Ducati, so I can't comment, but here are some thoughts for you to ponder
I started riding the Honda 4 and the Ducati without a licence, so later I went back and bought a 250 to get my licence proper. Glad I did. It taught me how to ride again. Then I got my P's and straight away got a 750, then another 750 (later model) then an 1100, and from then on apart from one bike for a short period, all my road bikes have been 600's.
I learnt that if you can get over your own ego, a 600 is just so much more rewarding to ride in almost all circumstances. Unfortunately most blokes have this penis/ego issue and have to have a manly litre bike. Me, I let my riding do the talking not my bike.
My 636 makes around 112 at the back wheel, and weighs something like 163kgs or something silly. I am a "C" grade racer and cannot get to the limits of the 6 on the road and still live

I have never had a bike overtake me up a spur run, not even a 1000.
If your one of those people who enjoy wheelstands, and the biggest lean angle you ever get is on the sidestand, then maybe a 1000 is for you? If you are a corner carver and enjoy a lightweight, nimble, quick steering but stable performer, go a 6.
I know when we get home at the end of a ride I am usually fresher than most of my mates who ride litre bikes. They are heavier, and harder to ride. They have more inertia in the motor to overcome to turn the bike. The power comes in harder earlier, which can catch out the unwary wuite easily.

"I hate to advocate drugs, alcohol, violence or insanity to anyone, but they've always worked for me" Hunter S. Thompson.
There are really only two questions in life. 1.Which way do i go? 2.What is the lap record?