You may also want to consider https://powermetercity.com/product/fsa-road-powerbox-alloy-crankset-power-meter/ it is dual sided power at the crank, its batteries get hundreds of hours before a quick replacement, it auto calibrates every time you stop pedaling for 3 seconds and has temperature compensation, it even has an LED that lets you know if your connected, it's woken up, etc.

I bought it a few months ago, have about 800 miles on it, and it's been perfect, my only gripe is it's extremely heavy, but you'd be saving hundreds in comparison to almost every other system.