Go for more int rather than more dex. Riot armor isn't "bad", it just generally isn't the best choice. It is the best choice vs melee if you aren't wearing super heavy metal armor or maybe infused sea wyrm leather with dense padding. Normal is actually easy, and you're a TM energy gunner, so you should only have any trouble near the start of the game.
I would put your spec points in high technicalities and crit power.