After having played a few games with threemo yesterday there's quite a few things I really feel need to be in his lists that will hurt him in multiple list steamroller environments due to character restrictions. Sure the Thunderhead and Strangewayes wont need to be anywhere else, but there are many other key character solos/units that really make the list hum dangerously
The biggest problem is gonna be Reinholt. So many of our casters really love bringing the gobber along and the competition will be fierce for who gets him. N3mo's gun is so useful, and the second shot gives you some real scary capabilites. Hell, with that second shot on feat turn you can vaporize squishy high def casters from VERY far away with overboost and 4d6 pow 10s. This probably will mean n3mo gets paired with one of the haley's or strykers, but limits his pairings with both caines, siege, sloan and others.
Piper will also be in contention for use with N3mo, since he has no troop protection spells your limited to Juniors arcane shield and pipers tough. Since you would usually rather AS be on a Stormwall or the Thunderhead, you leave all our stromnouns sitting at 12/15, and tough is gonna be almost necessary to help them stick around.
In all my games yesterday I also brought Aiyana and Holt in his list. They solved ALOT of problems for me and I can definitely see them going in n3mo's lists above all others. None of our lightning guns are magical you see, and that will either A) force you to use Chain Lightning a bunch or B) take B13th, ATGM's inorder to get some magic weapons into your list. Aiyana+Holt not only give you magic weapons so your Thunderhead can pulse incorporeal models but can also turn N3mo's boss lighting gun into a magic weapon also, all the better for zapping passaged jacks and wiping out units of choir or the like. Not to mention that lots of high armor can be a problem (one of my games put me against 5 titans o.O) and harm will help you crack that armor with much greater efficiency.
Overall, I think n3mo's growing on me. At first I was on the fence about it all, but once I watched a stormclad under feat turn scrap a heavy with his sword while the electroleaps scrapped a nearby light jack, I was sold.
If only finch didnt have 12 armor