I've went from 5 shamans, maxed them out in heroics and switched to pally and druid healer for a chance of pace... with 5 shamans you will die a lot, but when you get going and get the gear you need you'll fly through instances... pally and shamans plus healer is slow, but more safe... I imagine you can finnish heroics with less gear than my shammys did. You'll never go anywhere with 5 shammys in pvp, you need another person healing, period. With the xpac on the horizon I'd suggest going pally + shams, 5 shams won't be what they were before with the change to bloodlust and ToW and you'll still have a lot of fun.