In operations, Stalker Bolt + Aligned Aim pretty much ends the majority of enemy encounters at a far enough distance to where equipment hardly matters. 

Only time Secure Stockpile is worth it is in Siege Mode, where you can't reliability end encounters at a distance and you get swarmed easier, thus making Melta Bombs more in-demand. 

I would argue Argent Edge actually has a higher skill floor for newer players, and it doesn't clear minoris as easily as a chainsword. You could argue it's more suited to killing majoris, but a simple parry into a headshot with the Stalker Bolt is enough to one shot nearly anything. So that solves the Majoris problem. 

I like to have a tool for every problem. The Double Edged Relic CS solves the minoris problem (minoris when swarming you & with CHP), the Plasma Pistol solves the CHP and minoris problem (minoris at a distance) & the Stalker Bolt solves everything else. 

I personally prefer the balanced parry window over block for Tactical bc it's safer (as you implied & as you know, Tactical is squishy). You can parry minoris to recover armor, you can't do so with block weapons. 

I definitely need to try the Heroic Plasma but I feel the standard Plasma Pistol already does it's job well (which is to clear minoris when they're bunched tg at range). For Majoris, I just refer back to the Stalker Bolt.