AS a die in the wool biker I would have to say no. Simply for the fact that simulating the feel of a bike to GT5's adsacting standards would be practicaly imposible at this point. By this I mean Kaz likes things perfect, the feel of driving a car is all important in the GT series, actualy making that same feeling or same imersion for the player in regards sitting on a bikejust wouldn't work as well.
Many games try, and to be fair there ok but ok isn't good enough for GT5. A car has you sitting in it prety much straped down to the machine, a bike is totaly different, you basicly using your whole body to control it not just your hands and feet as in a car. And to the "casual gamer" or to those not used to rideing a bike it would be very frustrating, Try this on for size, counter steering, your travelling at 30mph+ and you are aproaching a left hand turn.......in a car you turn the steering wheel left and round you go. On a bike you lightly turn the bars RIGHT which causes the bike to lean to the left, you then adjust your bodys weight and balance to control the amount of lean as you go around the bend, the more you lean the tighter you turn which is also dependant on your speed, your imput to the bars is more keeping them steady and as for steering imput there only realy used at low speed. how would you simulate this on a pad?