I have been using the Moxy Monitor for athlete testing and personal monitoring since Oct 2013.  In my opinion the Moxy Monitor is THE only training tool necessary for any athlete as it indicates your state of physical readiness to continue with your training based on the oxygen content in your muscles at the capillary level. 

Moxy can indicate what YOUR limiter is when it comes to progressing in your sport and help target your training towards improvement because it is the ability to stay rested and injury free that allows us to absorb the training, not the training itself that makes us stronger, faster and more efficient. While we use it to test which gives us training zones based on energy substrates, that is like determining your financial situation based on your bank balance on a single day.

Owning your own Moxy Monitor is preferential because we are dynamic and ever changing so while the heart rates at a given point bring us closer to personal knowledge it is the daily collection of data that let's us know if we are absorbing the work we do. You can get more information by visiting their website at http://www.moxymonitor.com/