One of the bigger problems with the new White Dwarf army list for Sisters is that it doesn't scale very well - you get a d6 Faith Points regardless of army size. That got me thinking that Sisters might be competitive in low point games like Combat Patrol.
Here's one list I came up with for Adepticon-style Combat Patrol (400 points, no models with 3 or more wounds, no 2+ armor saves, nothing higher than AV12, minimum 1 troop). I'm sure a veteran Sisters player could come up with something better, though. What else does Sisters have that's good for low point games?
400 Points:
Battle Sister Squad (10) with Heavy Bolter, Meltagun, Combi-melta
Dominions (5) with 2x Meltagun and 1x Combi-melta, in an Immolator with a Heavy Bolter
Retributors (5) with 4x Heavy Bolter