Popular class combinations

[letxtc]

I have been trolling here for a long time and have noticed that the popular group makeups are 5*sham or 1 pally and 4*sham.
Now I have been dual boxing for a few years and have just moved to a 3rd account. I plan on making my way to 5 boxes once i have the hardware.
I plan on having the following group makeup.
prot pally (tank) main (lvl70)
resto sham (healer) bot - tots and healing (lvl64 lvling)
mage (dps) bot - easy one button dps with sheep option (lvl70)
mage (dps) bot- easy one button dps with sheep option (new)
lock (dps) bot - wife is leveling my lock here when we play together. might lvl a mage on this account too to make life simple. (lvl65 or new mage)

So can someone explain why tank+healer+3dps especially the 1 button mashing sheeping mage is not the optimal group setup?
For some reason I feel I am overlooking some glearing flaw with the mage bot.

[Ughmahedhurtz]

The original heroics guys used to run almost exclusively tank+healer+3dps. When folks showed that tank+4sham or 5sham could do it AND be viable in PVP, people switched pretty quickly. :P

[Naysayer]

The original heroics guys used to run almost exclusively tank+healer+3dps. When folks showed that tank+4sham or 5sham could do it AND be viable in PVP, people switched pretty quickly. :P

With the huge buffs they are giving warlock pets in WotLK, especially VW's, I'm wondering if they'll become viable meatshields eventually.

I'm sure there will be some definite 5xDeathknight viability as well. Can't wait til wotlk.