While further contemplating my army list, I have gotten the feeling I need another flanking unit. Atm my only one is the Doomwheel, which may well be out on its own duties and cannot be relied upon to be there for my main line. Sure, gutter runners can pull off a flank charge but are not a durable option, and cannot make a dent in armoured foes. I really like the gutter runners, but I think I'll drop one unit to make way for a unit of Rat ogres.
My army are quite agile and have decent shooting, but when locked in combat, they might struggle to deal with the enemy. The skaven can hold, and even shoot at the slaves opponents, but you really need something to bump that combat and win. Otherwise the units will surely be grinded down, not to mention my characters.
I think I'll try a unit of 2 rat ogres, one of them being a master-bred. The master bred is really a great upgrade. In addition to having +1 ws/a/in, it also makes the unit more durable by forcing opponents to distributing wounds between them. A plus is that the master-bred is very capable of winning a underdog challenge with his 5 st5 attacks + stomp.
103 points for 9 s 5 attacks + 2 stomps and a s3 att is a good investment for helping my other blocks out. You'll need to keep them within bsb and/or the general for a sort of control over their frenzy or stupidity.
The main tactic with these would be to hang back a little, keeping in potential flank arcs and not committing to units I don't wont them to. These guys wont survive a frontal charge at anything but the smallest units. Their ini of 4/5 is great for making sure those attacks get to hit and will sure count, especially when fighting other monstrous infantry.
Oh, and did I mention the IoB models look really great! Reason enough to get them.
I still have one gutter unit left still to potentially hide my assassin, which is nice.