bureni it depends on how the engine develops power. Technically you are only restricting the top end but if you've a high revving, ie gixer 6, motor that only produces power higher up the rev range and has little torque, you affect acceleration too. A v twin, which has much more low down torque, even in the low capacities, only affects the top end, with no acceleration loss. That's why if you're on a restricted licence it makes more sense to ride something like an SV650 than an R1. I'm assuming that this would translate to cars as well but am no engineer, so fine to be corrected, a diesel and petrol motors produce power differently, you can feel it when you drive. You don't get v twin cars any more but there are v6, v8, v12's, generally the cars with greater power, I don't think restriction would affect them in the same way but then it's rare you see someone stuffing a Ferrari on a motorway, one of the safest places to drive in the UK.
Strange the Government haven't yet seen fit to put the same restrictions on car drivers, I'm assuming the car lobby wouldn't let them get away with it. From January anyone under 24 will have to jump through many hoops to get on a larger capacity bike, with at least 3 tests or wait till they're 24 and go the direct access route.
BTW it's inappropriate speed that kills not speed itself. inattention is the biggest killer on our roads "sorry I didnt see you" translates as "sorry I was too busy texting, tuning the radio, doing make up in mirror, shouting at kids, am so safe inside my steel cage I don't need to look" delete as apropriate. I may sound bitter but that is an excuse used daily on our roads, compulsory riding of a motorcycle or push bike on the road for 2 years would make all of us that drive cars better, and more aware of other road users and hopefully fewer deaths.
LalyRaw so sorry for your loss, its hard to loose anyone but senseless accidents are incredibly hard to come to terms with. I don't know how you coped at such a young age, or how you're still coping. :(