This is stunning and the layout of the unit frames seems pretty intuitive to me (at least I assumed it to be pet, focus, self, target, ToT and ToToT). I am consistently amazed by the level of detail you put into your panels but this one is the best yet. Really, really nice work.
(Shame I am not a pet class or I would try to take inspiration from the frame layout!)
The horizontal gradient frames are amazing; I'd love to use something like that in my UI. I could see myself using the vertical ones, but it would take a heap of getting used to and I don't think it's as aesthetically pleasing to the eye as the horizontal are. Have you had a play around with pitbull4?