I have actually had very different experiences. My latest 750 point build is two Battlewagons with killkannons, each of which holds 12 slugga boyz, and a trukk with another dozen boyz. Two mobs have
PK nobs, and the third has a
KFF mek. My recent opponents are just about ready to throw me off a building. Two ordnance-toting AV14 transport vehicles full of
CC monsters in 750 points just really seems to throw people off their games. Very few armies I've played have the firepower to seriously threaten my heavy vehicles.
This army came about when I fought a 750-point army with 96 Orks in it that utterly crushed me and left me a real appreciation for the lopsided army. Just like I simply didn't have enough guns and axes to kill 96 Orks, my guess was that other 750-point armies simply wouldn't have the firepower needed to destroy two ordnance-toting AV14 tanks. I seem to have been right so far.
In my recent experience, the only thing that will take it out is an army with a lot of long-range anti-tank firepower. Short-ranged anti-tank won't work since the vehicles are full of boyz! Same goes for
CC generally. The hidden
PK nobs frighten monstrous creatures and characters too. The poor players whose armies have a lot of anti-infantry firepower get frustrated very quickly. And a frustrated enemy is an easily manipulable enemy!
It's a weird build, and a risky one I'll admit, but none of the armies I've fought lately have brought enough long-range anti-tank firepower to threaten the battlewagons shielding the trukk. I have to choose my battles very carefully since with only 36 orks, I'm often outnumbered! However the danger presented by my wagons and the mobility afforded by the trukk has allowed me to put my enemies on the defensive usually from the first turn. And when you get to choose the time and place of the battle, you win!
Now granted I haven't fought any Tau with this build yet!