A bunch of interesting observations and I've had a few of my own the last couple weeks. My initial thought of running 2-3 big blocks of Marauders has definitely changed quite a bit. Right now I'm running just one big block of these guys with 2 18 man units of Warriors and a unit of trolls. It's more flexible and seems to work a bit better.
Magic and War-machines seem to be the bane of big blocks of Infantry right now, there is some nasty stuff out there. I've added 2 Hellcannons to my force right now (although assembly and painting them is turning into a major chore) and they've done really well. Overall, my WoC army has been undergoing drastic changes, from Cav heavy to Infantry heavy...looking forward to Ardboyz and seeing how well it does.