For the most part PERP guns are adaptations of models from older mods. This is a newer rifle, meaning finding someone who has a fully working and animated model of this in the source engine who doesn’t mind it being used and edited by perpheads would be a chore. Old engine, new gun.
That being said the MCX / MPX series of firearms in general would be nice, if a modelling dev can get this working and added I’d be interested in using it.
comes pre-packaged with a suppressor, which makes it stand out as an option to some people as their main weapon
The suppressor on the MCX spear isn’t actually part of the rifle, only part of the military experimental phase kit-out. Whilst if the rifle is drafted in service it’s probably retaining the use of a suppressor, it isn’t actually permanently affixed to the rifle. The weapon is designed for all intents and purposes to be suppressor ready, but it’s not a permanent part of the gun nor really is there any functional dependency behind its use.
If you specifically want an MCX because of having a built in suppressor added, the MCX Rattler “Canebrake” model, in .300 blk, would be the model filling that purpose, and would also add a new caliber too:

(This is the goofy pistol configuration of the gun because of those wacky American SBR Laws. It does accept a stock just like any other MCX series rifle.)
If any rifles were to be added though and if a modelling developer is willing and capable of doing this I support the idea. I think though that other variants of the MCX could / should be added alongside it. I have faith in the developers to be able to achieve making new weapons.