The beta’s over, and I’m waiting to get some cash for the pre-order but I still remember the build I had for Oscar Mike; it worked very well for me.
Helix 1: Impact Trigger
(Grenades Detonate on impact)
I use this because I hate having to anticipate when the nade will explode. I just pop it and drop it, and usually at a player’s feet.
Helix 2: Fragcendiary Grenade
(Upon detonation, Frag Grenages blanket an area in napalm, dealing damage over time to nearby enemies. +360 Damage over 6 Seconds)
I use this because I love AOE attacks, and this is very good for finishing off a fleeing enemy, or scaring people away from a choke.
Helix 3: Red Dot Sight
(Fits Oscar Mike’s Assault Rifle with a red dot sight that enables full-speed movement while aiming down sights.)
I like not moving like an old man when I aim.
Helix 4: Back in a Jiff
(Activating Stealth Generator prompts Oscar Mike’s shields to immediately begin charging.)
I typically use stealth when I need to run away, quickly. I usually am only using this to push behind a turret, or to avoid being eviscerated by a Rath by running away like a b*tch
Helix 5: Doubletap
(Doubles the number of Tactical Rounds in each magazine. +15 Tactical Rounds)
Moar constant damage! Plus I use the OTHER shield penetration skill.
Helix 6: Stealthy Shields
(Increases shield recharge rate while Stealth Generator is active. +105 Shield Recharge Per Second.)
I’m less likely to die while I’m running away. :3
Helix 7: Disruption Rounds
(A portion of Assault Rifle damage penetrates enemy shields. +25% Shield Penetration)
Because this is more useful then the other 2 options at this level.
Helix 8: Embiggened Boom
(Increases the effective explosive range of Frag Grenades.)
Moar AOEEEEEE!!!
Helix 9: Operation Sneaky Ghost
(Increases Stealth Generator’s maximum active duration. +6s Duration)
I can run away even LONGER with this! 
Helix 10: Holy Crap, Concussive Strike!
(Enemies damaged by Airstrike are slowed for a short time. +3s Slow)
Because I like showing Rath what it feels like to be slowed by a powerhouse class. ;3
As for items, I just used whatever gave me faster reloads, less recoil, health regen, and more damage. Balanced, ya know?
I really only used this build for PvP, and I’d imagine I’m hardly the only one who plays like this.
I do my own thing and take out buildables, turrets, and LOTS of shards. I love collecting those buggers, and the less shards the enemy has to go around, the better!