No, not much difference. You could say that the 450 crank would last longer because it is carrying less mass with the same size bearings as a 525, but you could also say a 525 doesnt' have to turn RPM's to make power, so it will last longer.
In the end, buying a used bike, your reliability is going to be a factor of the condition you bought it in and the condition you keep it in. Anyone that tells you that one brand is less likely to break down than the other or is faster/lighter/stonger/cooler probably just owns the bike they are hyping and doing it only to boost their own ego.
Choose a bike that you can go and personaly look at and ride. Choose one that has a transmision that fits your riding style and area.