So I noticed something last night: I helped a friend run a lower level story dungeon, and noticed significant progress on my XP bar when I was done. Now, I'm used to games with level synching, but I'm not used to synching down and having the XP gain at the lower level content be significant to my true level.

Is this the case in FFXIV? Could I, potentially, (not that I'm planning this) run the very first dungeon, or FATEs in low level areas, all the way to 50 with significant XP gained each run due to level synching? I'd certainly apply this to more... PUG-friendly guildhests at lower levels.