The site is bugged and doesn't count the 5 piece for some reason. This is 354,000 base skillpower and 50% skill haste in game. Showstopper for quicker stacks. Skill power soft caps at 450k, which you will be at most of the time. The pulse will give you good damage to easily beam other players' support stations to keep stacks and talented up most of the time. I prefer 393k toughness because with a maxed out pulse and overheal you can actually ads and safely do decent damage. You can run less stam and survive pretty easily with the vig chest, but the only benefit there will be an improvement to your base skills before stacks or talented, because at full stacks the difference between a 325k toughness and 400k toughness build is negligible. I find that at 393k I am able to actually shoot and keep stacks up easier than when I run this build squishier.
No Barrett's because I'm usually at max skillpower anyways so the 10% won't help much, and its rare that I'll have both skills off cooldown at the same time.
No inventive because, again, I don't need anymore skillpower. When I am at low health is when I want my heal to be strongest, and my pulse already caps my teammates' crit chance at 60% so the 15% skillpower bonus from inventive would needlessly just apply to my pulse most of the time.
Trained is actually a great talent to use on showstopper. If you dump a full mag into an NPC, that is 8-10% of your ult farmed back instantly. The only other talent you could use is competent, but you don't use the showstopper for damage so that is pointless.
Compared to FM pulse build, I definitely ADS more often and do more damage with this build. The pulse is way stronger, and with the vig chest I have a much larger health pool.