Not yet multi but considering how many characters

[Pokeit]

I've read through the forums and tried to sort through outdated wikis etc

My main character is pretty well geared and I enjoy him. Working on as many achievements etc and he will be my main focus in any endeavor; however, due to the mechanics of some old fights and that annoying ?? Boss classification I am unable to do certain old world tasks such as Raptor mount in ZG. I've found myself dependant on others for simple tasks and it is frustrating. However since my primary is a dps i'm not sure if dual boxing is sufficient since I'd only pick up either a tank or healer.

[edit]The monkey wrench in this scenario is that my main is a Rogue. Therefore I have a melee class in the arsenal that isn't a tank. So how does this change some of the original suggestions? (I forgot to put it in my original post!) [/edit]

So my question is this: what is the recommended number of characters to box?

I'm being drawn more to the dark side of 5 after having been crushed by 5x lightning bolts in pvp of course But I'm not sure if that is a logical decision. Running heroics without 15min queues sounds nice too... then again practically maybe 2-3.... I've read somewhere that 4 is pointless, either cut at 3 or go all out for 5. Or would a simple dual configuration work?

So Advice?