I have a thought regarding persistent techniques in general. One idea to better balance them is to make the initial outlay of energy equal to that of normal honed and epic techniques. The benefit of the persistent techniques should not be the initial outlay. It should be the fact that you can maintain them, round over round, at a lower price. By making the initial outlay of energy equal to a normal honed or epic technique, without getting the same high levels of bonuses as a one time Honed or epic technique, you bring things more into balance. I feel this would help.
No, they don’t provide the same level of bonuses, but that’s the point. They’re not as good in the short term, for the same energy price, but they have the benefit of use round over around.
I think some of your concerns regarding that might disappear if you do this.