Honestly, it all comes down to your intentions, budget and patience.
If you plan to daily grind to higher levels, sometimes any gears will do. Amp's and gears only make such a thing easier.
If you intend to obtain arena gears, such as lvl17 or 19. some people prefer to amp lvl13 gears and acquire them in lvl 14 arena or lvl to 15 and join an AP farm. If you do not feel that lvl13 gears will be suffice for grinding dailies for high levels, such arena gears will make things a lot "easier".