iv heard trusts with new xp rings. I recently lvlved a few mules just enough to use the mog tablet kupo power to tele between nations (lvl 20 i think) And while it was fairly fast, i noticed skills certainly get left behind. I would imagine as i lvl that that would come back to bite me. Even at 20 fights started to take a while because i was missing 80%+ of the time.
Edit: granted i should have decent skills on main char.
skilling is faster than ever, so it shouldn't be too much of a problem, at least it will be way better than skilling after burning, not to mention you can always get skill books.
I did sam the other day, used a polearm instead of a GK because my GK skill was ***, and I was killing colibri anyway.