Permanent DST was tried in the 70s... I think it lasted a month before people got fed up with it, especially in the parts of the time zones that were the farthest West/North. I'm in the Eastern part of the EST and it would be dark until 8:30 am, and would still be dark when most people leave work.
I'm guessing permanent ST wouldn't go so well in the summer in the Eastern parts of time zones. I do like the 5 am sunrises, since I get to work by 6, but 4 am? Doesn't sound appealing.
So as much as I hate to say it, I think spring forward/fall back should stay: just change spring forward back to April so the change to dark mornings is not so sudden, and keep the fall back where it is.