My group is doing an Ascended+ campaign (mixed PCs from all 3 40k RPGs) and we've noticed something that I see many others have noted on these boards. The Storm Trooper is... pretty underwhelming when compared with any of the other Combat focused careers. They're really only worthwhile if they have the resources of a full unit to back them up, individually most of the other careers are far better.
But, despite so many people agreeing on this, I've found almost no suggestions on how to fix it. (If there is such a discussion that I’ve missed, please link me too it.)
My personal view is that the core of the Storm Trooper's problems is that their guaranteed Ascended Trait, Special Operations Training, only works with Hullguns and Carapace armor. While it does some nifty things, allowing them to nearly reach the performance of power-armor and bolter, that equipment is losing its usefulness at Ascended levels. The Storm Trooper is at their most effective the moment they Ascend. From that moment on, assuming they stick with the gear they have their bonuses with, they will slowly be outpaced by their opposition and allies. In order to stay competitive they need to upgrade their equipment within a rank or two. And as soon as they do that, they effectively loose one half of their Ascended special abilities, which puts them right back behind their foes and allies in individual ability.
My proposed solution would be to extend the bonuses the Storm Trooper gets to Hellguns and Carapace Armor to all Imperial Issue weapons and armor. That way they retain their special abilities, and can scale their equipment with everyone else.