Apologies for the delay in replying. Here is a reply from UA director of coaching Chantelle Robitaille to your questions:
There will be an article coming out about RPE.
Don’t think of this so much as a shift, but an alternate way to guide training.
Our mountaineering plans are available in both formats.
Our running plans are in RPE because it’s a better fit to guide intensity for runners on varied terrain at varying elevations.
Re. HRV, nothing new has been published and there is no plan for that. HRV is one among many metrics that athletes can use to gain information about their training readiness and level of recovery. They should consider all metrics available to them to make good decisions for themselves- but that means BOTH subjective AND objective data. For anyone keen to learn more about HRV and how to use it, the foremost expert in this area is Marco Altini, PhD. https://marcoaltini.substack.com/
Let us know if you have other questions,