i leveled another 2 toons: a lock and a priest, so now i can experiment a bit:
account 1: prot pala
account 2: holy priest
account 3: fire mage
account 4: ele shaman, warlock (probably destruction, never had one)
account 5: balance druid, shadow priest

yeah i know, i can't make up my mind

advantages of the group with lock and shadow priest:
4 x wanding!
imp health buff + imp dps
VW for offtanking
succy for cc
healthstones
curse of the elements (helps all 3 dps)
more AOE spells
a lot more cc
more that i'm forgetting?

disadvantages:
no 8% crit
no motw
no totems

it's not 5 different chars anymore, but still 5 completely different specs!