How much do you weigh?
A 600 and a 1000 are no different in the fact that you can kill yourself either way, you can be a brand spanking new rider with 0 experience, and still hop on a 1k and be fine, it's more on how YOU are then the bike.
I myself started on a 250, then a 600, now on a 1k.. everyone's different. I only started on a 250 because It was 4500 brand new with 0 miles, and got 70MPG, but it did get boring after a while.
I jumped on a 600, which was tons of fun, then decided to go to my 1k, because I just overall loved the bike and always wanted one, and wanted something with a bit more power.
If somethings wrong with a bike, you will know right off the bat,
I would never buy another bike brand new, it's a waste of money, you can have the same bike for half the price, with under 10k miles, which on a bike is nothing wrong at all... but to each their own..
All bike manufactures are fine, everyone has personal preference, I like kawi's and Honda's myself.