The thing with Lv sync, everyone who has a problem with it, always base it on the FLAWED version of it in FFXI.
The concept of Lv sync isn't the problem. it is how it is implemented that is the problem.
(aka, no skill ups, better exp on lower Lv mobs, because most mobs give the SAME exp, etc)
Higher Lv mobs should give more exp, not because the ones u fight now, slowly give less, but because the actual number is HIGHER.
(aka Lv30 should give LESS to a Lv30, than Lv50 gives to Lv50s.)

With yoshidas opinion on PLing, I think this is his alternative/answer for now.
(Personally i HATE having to withhold leveling multiple classes, just to play with friends.)