As I said a couple posts ago, I found Overload useless for everything other than CC.
Keep in mind that I can play maybe 10 characters well on Gold (the list was recently expanded with 2 more non-infiltrator characters, yay!), and TSent is definitely not on the list. However, this build does work for me - it's not as powerful as some classes I usually play Gold with, but it's solid. I understand that if experienced players like you are saying Overload should be used - there's a good reason for that, but I don't understand that reason yet, and it won't do me any good if I spend points on Overload without understanding what to do with it to make it worth those points.
Warp is not offensive ability, it's a support ability thanks to its debuff and BE priming. I'd use it even if it had 0 damage. And Valkyrie is there because I just unlocked it, and it's a Turian character - Turians are good with assault rifles, so why not try it out, I said to myself. It's not a bad rifle, too. But, ofc. Harrier is better and there isn't really any reason to pick anything else for a non-soldier character. But I don't like camping ammo boxes all the time.