Unfortunately, hard pass from me. It would cause people who are actually the intended level for a run to feel practically worthless. I'm thinking the lower-level dungeons in particular. Hey, my RDM being synced down has his full tool-kit with multiple AoE spells and a high-powered combo. You, our newer player just reaching that dungeon for the first time, don't even have a single AoE ability yet. Entire packs melt and all you got to do was a couple single-target attacks against one mob.

Syncing the skills as well gives everyone in the party the ability to feel relevant, while still giving higher-level players being synced down a bit of extra power (since it syncs to the max level for the area rather than where a leveling player would likely be gear-wise).