A few things I've noticed while playing:
If you load rockets into the rocket launcher, they don't "stay in" the rocket launcher like the other weapons. If you use up all of your rockets firing grenades out of the chaingun, the five rockets loaded in your rocket launcher mysteriously disappear. Not a huge deal, but it caught me off guard.
I've never felt the bullet firing function of the chaingun was very useful, I rarely use it. I usually don't like guns that need to warm up while firing (I hate wasting bullets, and it doesn't feel like I'm in control of the weapon).
The sawn off shotguns and pistols are semi automatic, whereas all of the other weapons are not.
I can see why you did this, but I'd really like to see an option to just hold down the fire button and alternate guns for the pistols and sawn offs. Keeping track of fire, alt fire and reload is kind of tough in an intense firefight.
It'd also be cool to have an option to automatically reload the weapons when you try to dry fire (try to fire with no bullets in the chamber). The sawn offs already do this, but the plasma gun, pistols, and normal shotgun don't.
I'm not sure if you can do that, I know Psychic had an option to switch the weapons between semi and full automatic, but I've never heard of a menu option that would do that last part.
EDIT - here's the super large zorcher with the parkour mod

That's one of the weirdest yet coolest things I've ever seen. The reload frames look really cool if you don't look at them too carefully.

EDIT2 - I posted links to this mod on the
CQFF, I hope you don't mind. This is one of my favorite mods.
EDIT3 - never mind... ultimate doom is missing a lot of sounds, from monsters, etc., there's not much point in fixing that.