Well, here's the deal. I've only heard positive things when it only involved the replaced connectors.
I have been around RC electronics enough that I know there is nothing gained by replacing the lead wires from the Tamiya electronics and when such a short piece of wire too. AND, there is little gained by replacing the motor wires too, unless we're talking about a total re-wire.
But trust me, if the failure surrounds something that we changed I bet there will not be a warranty at all.
So make sure your little soldering job is right.
~ Jeff