I do run my 12 unit as 4 x 3. I find that configuration is very versatile. It is small enough to fit through scenery and offers a +2 bonus on strength for the charge.
I also usually put my SlaughterMaster into this unit.
The ironfists make it a very tough unit to kill, as well as if I get Trollguts on it.
Good choice on army by the way, at least in my opinion. Just today I sold my Dwarfs, because they are so boring compared to the Ogres. So much flavour in them.