You do know that the Stryd was developed by two well-funded (primarily by NSF) PhD faculty in electrical engineering? They may not be experts in exercise physiology and biomechanics, but they know they're way around instrumentation.

Reliability (reproducibility) of the data is actually adequate. In my tests, for example, the CV across days is <5%. The results also correlate with force plate data, and are sensitive to individual differences that you would expect to find based on the literature (e.g., children need to generate more power than adults to run at a given speed).

I do agree that triathletes are a perfect target market for such devices - just look at the success of things like PowerCranks. Unlike that product, however, the Stryd appears capable of doing what it claims to be able to do, i.e., quantity running power (and other parameters) with adequate accuracy and precision.

The question is therefore not "Is it any good?" but rather, "How do you best utilize the data?" That's what the charts I have developed are intended to help with, and what we* hope to explore over the next few years with support from USATF and the USOC.

*Steve McGregor is the PI.