We had a discussion about HRV on the forum a while ago. HRV integration with Xert Freshness / Fatigue Chart and Recommended Workouts At that time Scott said that they did not use it. Also I suggest you might like to read some of the information on readiness scores etc on the HRV4Training blog. Maarco Altini is one of the foremost experts on HRV. HRV only is useful when taken in context of other factors from what I understand. I have been using it for a couple of years and I do use it as a general guide to what sort of intensity I should consider. Also there is a new blog entry on the Xert blog about readiness. Have you read that? Assessing Readiness to Train – Xert or on the forum: New Blog: Assessing Readiness to Train - #6 by ManofSteele
I find HRV interesting.