I started of with 2, then to 4. (pala/2x mage/holy priest)
Couldn't really do any boss in WotLK due to bad gear.
Got an extra account, transfered the pala to a new one, and used the hunter i got on the ex-pala's account.
Everything goes much better now, last weekend i farmed 28 badges of conquest to get a nice belt.
With 2 chars, you'll really be wiping all the time.