Since you guys are on the topic, I completely stopped using firearms for my custom troops and turned them into versatile desert warrior/assassin types instead. Kinda like a mix between the Sarranid Yeniceri and the Tabardariyya. Ymira is still using a flintlock rifle though, just for fun. Might let Artimenner use one too, if I decide to add him to my party at some point.
I have no strong archer type with my new army composition (my "archers" are actually better at melee than ranged attacks) and only a few heavy armor/shielded troops (some of them are actually just the mercenaries). Took a video of my siege of Sharwa Castle where I ended up with 32 killed, 176 wounded (versus 775 killed and 27 wounded). I got uncomfortable because we were taking lots of casualties and retreated, not knowing there was only like 30-something castle defenders left. When I besieged the castle again I just let them go peacefully. Don't want to risk any more of my foolhardy warriors.
... I think I get way more casualties now than ever before lol. I'm so used to fighting against the Sarranids, and I used to get less than 100 total casualties even on big sieges. But it's still fun inspite of (or maybe because of?) how squishy my troops are. They're fast and move around the battlefield easily, and because they have various ranged weapons they can kill while on the move. I definitely had Sarranid tactics in mind when I put them together, and when I conquer the Sarranids finally (hence the siege of Sharwa), I'll incorporate them into the Sarranid ranks.