Thanks for your comments guys. I'm glad to explain:
Zaero, some of the ideas remind me of Crysis (the suit stuff) and a number of ideas I simply do not like, such as all the powerup replacement suggestions. If the SSG is no longer using default Id frames, what is the harm in having it as a monster drop?
What if there was a small chance of sergeants (and a slightly higher for commando) to drop usable frag grenades?
Yes, the whole suit-modes idea is indeed based on Crysis. Why? Becouse it:
-adds some tactical gameplay (you'll have 3 modes available but only one can be selected at time, so it'll be impossible to be invisible and invincible at the same time)
-those "modes" allows for permanent vanilla items replacement (as the modes themselves includes the "powers")
-it's possible to use the mode even if no item of such a type was available in that area (for ex. use radiation shielding near acid pool, even if no rad suit was available there). It's still balanced becouse of reasons listed above.
The powerup replacement is possible only if suit-modes are included.
As for the "monster drop idea": it would look quite unrealistic for monsters which don't have such a weapons to drop them. The other downside is the fact, that drops would be absolutely unpredictible (so the player could have a lots of ammo for weapon which he didn't found for ages, or vice versa). As for the "commando" - if he's the only source for grenades, then they're unavailable in Ultimate/Doom.
Sorry, but, uh... I would really hate to see all of that in Brutal Doom. Specifically the SSG replacing the Berserk Pack (seriously, out of all the pickup items in Brutal Doom, why the Berserk Pack?).
Becouse the berserk pack would be obsolete with the Berserk suit-mode available. The same applies to many other items as well.
The second reason is the so called (by me) Berserk-trap. Many mapers including Id used berserk as a decoy placed in a room full of demons/imps. What is the best weapon to deal with them? SSG (IMHO).
My idea also takes in consideration the sprites resources available, so I would recommend:
DarkClaw: Hexen's Cleric's 3rd weapon sprite, Heretic's gauntlets + flame hybrid as pickup
Unmaker: Is done already for Doom64, isn't it? There is no need to re-invent the wheel.
Grenades: One word: Powerslave. Both pickup and throw anim.
Mines: As the ones seen in "Stronghold".
ps. By "Devastator" I mean the "revnants shoulder missile launchers" etc - it's just a shorter rename suggestion.
Cheers!