I'd say to hack in a little circuit using the existing resistor, some wire wrap and hacking a header jumper from it to the power side to make an easily activated test circuit so it'll be easily reversed for doing some benchmarking. It'd be very interesting to see how it runs the two systems, clocked at both speeds.

I've got a pic somewhere of the incredibly fugly hack I did like this on the DuoDock's DeclROM power leg if you're interested.