I doubt it matters, but the old ones will be harder to find and if they wear out they will have to go in the bin.

Tamiya parts fit perfectly and are well made. I can't think of a single component that is better than the Tamiya part anywhere on the car - the only exception being the diff and that is only because Tamiya don't make an oil-filled gear diff. My car is all Tamiya with the exception of the diff, and the diff (3Racing) is the part that has needed the most fettling to get right.