these are all systems that need to be developed, tested and implemented upon the current system... i don't think it's plausible tbhI understand the need for curtailing the over-abundance of UL items, but I feel there's another way to do that.
Create more upgrade paths that require the sacrifice of other UL items.
Think about the other kinds of modifications you could do to items to entice people to make the upgrades, such as (and taking an already available upgrade path) :
EP-41 Military Adjusted (as is)
EP-41 Military Improved - sacrifice 2 Adjusted
EP-41 Military Modified - sacrifice 2 Improved
(Choose Path)
EP-41 Military Logi - Requires 1 Mod and 2 Combustive 7s - Adds increase ammo burn but also adds Arsonistic effects
EP-41 Military Bifrost - ^^ and 2 Cryo 7s - Adds increase ammo burn, does frost damage tick + slows mob
EP-41 Military Eir - ^^ and 1 or 2 Mayhem Restos - Adds increase ammo burn, does action based Lifesteal 5%
etc etc
This could be applied to a whole bunch of items right up to the top and requiring more and more UL sacrifice, but obviously the benefits need to in some way justify the inputs.
The main pull of this game is people's chance to 'find' stuff out there (given that most people, if I'm not mistaken, choose to hunt). Finding things has become so tough recently that it leaves those that choose that path wondering, what's the point?
i would rather: create an upgrade path that requires items like you said but improve the final item's stats like eff, ammo burn, reload speed etc