I bought my first PS90 specifically for Post Apocalyptic World (zombies) type of situations. I'm not kidding. I wanted something small enough to fit in a backpack, very accurate, high capacity, low recoil, shared ammo with my side arm, and super reliable. The PS90 seemed like the perfect rifle for that "niche".
Very soon after purchasing it, it graduated from a "niche" gun to replacing my AK for all things SHTF. I've been training with this weapon for about a year now and I can tell you it will always be my first choice (along with the FiveseveN). I can go from "grey man" to full second line loadout back to "grey man" in a matter of seconds and no one would ever know.
If I can give you some advice, if you would ever consider using the PS90 for anything other than a range toy I would get the USG model, even if you want to put a different scope on it. The TR model can't support BUIS of any kind (which is why I bought the Leupold Prismatic) and you can easily take the factory optic off the USG model and put a rail in it's place. The USG factory optic isn't that bad anyhow, it's black so you can see it against light surfaces and it has tritium so it glows when against a dark background.
Gun Pron (they're going to be SBR'd very soon):