I ran a company of friends for a while, NPC's is a no match for a propper character, in my games, players were able to slaughter swaths of enemy troopers with ease. Warcasters are extreemely powerfull, even more so if it's paired with a caster career.
I was able to tie them up for a while, only after I generated Arcanist/Pistolier like a propper character with 1 feat point. Otherwise, most enemies, even warjacks or other monsters are no match to PC's. It really feel like power fantasy, where casters reign supreme. Mostly because half of normal enemies can't even touch the character with DEF 14 and abowe.
Rules are somewhat different to WH, but mainly they are the same.