Note: I don't have any experience with the following allies option.
I have been thinking of adding Allies to my SMurfs.
Inquisitor, T. Armor, PsyCannon, Lvl1 Psyker.
10 Grey Knight Terminators, 2 PsyCannons, PsyAmmo.
It's pretty pricey, but it's very flexible. I haven't nailed down what combo of Weapons on the Terminators, but they are primarily there to pew pew and counter attack for my biker army.
Inquisitor goes for Divination for the re-rolls to hit producing 12 rending shots from the terminators, before all the str 5 stormbolter shots.
Then my bikers can focus on exclusively bringing the plasma/melta
Though I'm still debating if the huge chunk in points is eating too much out of the main force, esp. at 1500... which is yes, but I'm teetering on the edge of just accepting the coolness and rolling with it.