Got a few more ideas here for ya Anero.
Welcome PM/NPC
This idea concerns introducing players to Multiplex. Some of the newer players who step into MPX seem confused at times, such as entering a spar without a MPX gun because they don't know how to get one, or not adding any points to their gun, not realizing that they could. I suggest a welcome PM like what the trade building has when you enter. An example to include in the PM:
Or, instead of a welcome PM, add an NPC that says "
Welcome to Multiplex! Grab me for information!" above it near the MPX entrance, then add the relevant information to it. Whichever is less intrusive. Either suggestion should help assist players who are new to MPX and ease them into MPX's competitive environment a little better, and hopefully encourage them to stay.
In addition, I suggest moving the NPC that resets your spar stats and the NPC(s) that gives you the MPX gun, and switch places with them. The "GRAB ME!" sign gets quick attention and is easier to find if it was moved near the entrance. I don't think many players reset their spar stats very often, and so I feel its NPC can be moved towards the back of the building.
Reward variety
On the subject of rewards, here's one suggestion to add reward variety to motivate players.
For example on gun skins, let's say a player reaches 10k wins. They can now enter a new 10k MPX wins reward room (anyone can enter, they just can't grab the rewards unless they have the correct amount of wins, like it currently is now), but instead of just one gun skin to choose, they now have options: a Silver gun skin, a "Blood Red" gun skin, or a "Sapphire Blue" gun skin for example. This means adding more rewards, but the idea is to give a variety of cosmetic looks on the same milestone level for the player to choose from. In my opinion, this adds some uniqueness to players, since everyone uses the same gun.
Adding new gun skins with different firing sounds, different looks, etc., can be appealing, and they can become slightly more "exotic" in looks as the MPX sparrer achieves higher milestones to avoid the look of a re-skin, such as shiny effects or a sleeker MPX gun design. Basically, the suggestion adds choices for the player to choose different appearances to the MPX gun on a milestone, and adds increasing attractiveness to rewards for higher milestones, so not everyone will generally look the same.
The same can apply for the hats and melees too, all that is needed is creative ideas and some development time.
Ultimately though,
none of these are meant to change actual gameplay at all; these are only visual differences to add further variety for accomplished MPX sparrers to show proof of their effort, and that's it. The idea here is to motivate players long-term to go for more attractive rewards and stand out, without changing the gameplay.
Staff MPX announcement commands
We know there's announcements for gang spar and PK Arena, how about one for MPX's duo and Base Battle too?

(unless they already exist and I'm just terribly out of the loop)