I'm Level 17 LNC and I just got PUG to level 8 when I heard that I may be leveling the wrong class. Post BETA , there has not been any confirmed information if DRG unlocks by using /Pug or /Mar

However what bothers me the most is if Legacy Servers have DRG already running about and they switch to say... any non Legacy Server do they lose the DRG if they dont have the cross abilities leveled up ?

It makes no sense for SE to change the set up... so I think the Key to Unlock remains the same LNC / PUG the other classes are to leech abilities from.