Thanks for the offer to help with an app. If I get to that point, you'll know

The data is all cached during a run, and only written to the card after a button press. Same approach would be used with Bluetooth. The *highly* variable latency of writing to SD cards drove me to use a cached data model. Even with the additional stuff I might add in the future, there's room for over 20 mins of data at 150Hz.

As it stands, and it's not optimised in any way, a single cycle of data capture is well under 2ms, so it would be possible to up sampling to close to 500Hz and maybe beyond for specific use cases.