I had a Nomad 3 for a couple of years and looked at replacing it with an Insurgent.
However, I demo’d an Insurgent and thought that the two bikes were really too similar to justify changing. The Insurgent was slightly more confident descending but the seat tube angle felt noticeably slacker on the climbs. The Insurgent top tube felt quite a bit longer when seated pedalling which I didn’t really like.
I had never liked the wallowing mid-stroke feeling of the Nomad 3 rear suspension (I’m 92kg) – the Delta suspension of the Insurgent felt much better in this regard.
I also have a Following so eventually replaced the Nomad 3 with a Wreckoning.
Another thing to consider is that the Insurgent is the oldest model in the Evil line-up and is currently being discounted so there may be an updated version on the way.