Level Sync from FFXI worked IMO because it was optional. I think having a choice to experience the game with friends was one of the most amazing concepts SE had implemented up until that point. It not only allowed you to do fights with friends at the same level it also didnt require you to go out and buy all new gear.

Level Capping for content IE: Chains Of Promy, to me, was a huge misstep. Most people thought the storylines and overall arc from COP was probably the best of FFXI however (as changed recently) the required level capping dungeons and zones were NOT popular. It was probably one of the biggest mistakes if not THE biggest mistake in that expansion.

I think if we end up with lots of zones being forced level capping I will probably find something else to play. I dont see any sense in having us level and work out way up to level 50 to be capped for fights or dungeons. The penalty already exists where as you level past the point of exp you get nothing from mobs under a certain level. Giving me the option via Level Sync might be something I use with my friends but forcing me to cap against my will is a deal breaker.

If you want to restrict levels then why allow us to level up at all?