Loving Psionic Armor myself. Vet level 99 and 1296 badges so far. So, yes, have to say, I like it enough to have rerolled my main into it. And it's versatile enough to really go for a lot of concepts besides Psychic powers.
Regen just got buffed and so did Dark Armor.
As a Scrapper you really can't go wrong with most armor sets.
As for Primary, Staff just got buffed to help it's ST DPS, but I do believe it's still lacking for some people, but it'll still get the job done and be able to solo AVs. That said, most would still agree Staff is best on Stalkers.
Pick for concept on Primary just as one would on Secondary and the only thing that may really go wrong with for you is "Do I want all these powers now?! But I want some more pool powers! Aaaaaahhhhh!"