At your level the only bonus you get is the drenai racial which doesn't stack so one drenai in the grp is enough for that Any other bonuses come down to your totems and that's totally down to you. Less shamans means it's easier to play but also means you have less buffs. Play at the level you are comfortable with. You won't see any changes to your current play excpet things taking longer to kill - but that's what the booster is for