Oi! goodness, no need for me to test the horse with the skill.
Here he is after 6 obs trained. The 10% less energy is definitely off somehow. It took 5 trains to get him down under 75% so a .25 end gain on the whole set of 6. He would be near the bottom of his energy bar without this skill so it's definitely giving back more than 10% per train.
http://www.virtualhorseranch.com/viewho ... se=1587446