> I used a Satechi USB-C power tester and measured an 8% peak power savings using UASP. That means you'd get 8% more runtime on a battery if you do a lot of file transfers.

No no, even better! Peak power consumption is lower, but the same work is completed much more quickly due to increased throughput, so the energy required for the same work is decreased dramatically. Between the performance increase and the lower power usage I wouldn't be surprised if this reduces energy use by 50 %.