I'd actually go against a lot of what people say on this from my own personal experience - i think a lot of the comments of people saying the bikes will be sluggish/suffocated etc perhaps come from people who have already ridden unrestricted machines as yes in comparison obviously the top end acceleration is majorly reduced - but if you're a new rider you aren't going to notice it.
I went from riding scooters, to a 125, to a 636cc ZX6R [restricted to 33bhp at that point also] over 5-6 years. At no point did the ZX6 ever perform badly or seem at all slow it was pretty bloody fast id say actually
Also, unless you go out riding it with a wheelie-popping hooligan attitude/death-wish, i'd say its actually a very good way to learn on bigger bikes, perhaps even more so than using a 400-500cc bike as a stepping stone, as i found by the time i unrestricted the ZX6 2 years later i was so comfortable with the feel and position etc it made riding it unrestricted come very naturally and quickly without any of the hair-raising moments.
I mean if you're going to absolutely hammer the life out of it when its restricted perhaps that may cause some engine wear, but i used to ride at motorway speeds and everything below regularly doing over 10k during the restriction and its been serviced by garages and myself since now at nearly 20k and you wouldn't know its been restricted due to any wear n tear. I even think it might of made it 'break in' easier having it restricted to be honest as it wasnt stretched much for a long time but that might just be me .
I should add [not that technically knowledgeable myself either but it may be relevant] the method of restriction I used was the FI international kit which was a throttle limiter pin combined with inlet-limiters that restrict the fuel/air. Unless its changed now, at that time it around 150 quid as although the parts and kit are ridiculously overpriced you basically pay for the certificate that comes with it that the installing approved mechanic signs to verify the bikes restricted. And don't be tempted to remove the restriction before you're legally allowed to as many people do as you may get away with it but if you have an accident/get inspected you are royally F'ed friend of mine learnt the hard way, lost his bike, insurance didn't pay out and got a hefty legal bill from the other party in the accident.
Just my opinions anyway i'm sure many will totally disagree but personally i wouldnt worry too much about what you restrict just pick a bike you like and ideally maybe will continue wanting and using after your restriction ends.