Been on rideouts with two restricted 600’s one an R6, the other a 636 05 I think 
both were pretty punchy
ull be absolutely fine!
i passed my test & bought a cbr600 the next week & had no problems at all (unless u count getting pulled for racing the next day!), u will quickly learn how much more power is there & how to handle it & will absolutely love it :o)
I went from a restricted R6 to full power and loved it. Found the restrictor annoying very soon into my 2 year restriction.
I didn’t find it a problem getting upto 60 or even over a ton on the restriction though. I haven’t ridden a 250 Ninja so can’t comment on the performance compared to my previously restricted bike.
The 04 is identical to the 03 bar colours (I think they introduced black as one of the colours).
They also look amazing with this MotoGP style exhaust that my mate got for his bike from dan-moto.com.
Wow… nice.
I looove the sound of those things!
A bike only goes as fast as you twist the throttle…
I went from a 1989 400cc bike with 60bhp to a tuned 99 Blade with 132bhp…
had no problems, in no time, I got bored and wanted something better handling and faster.
It will be bad if you don’t! 
Maybe I can have a go when you get the bike?
Will be nice to feel the power!