Most of my victories in this game were acheived when I used the more defensive teams. I find that controlling the number of genestealers in play is generally more effective than trying to eliminate them as they are spawned.
Blocking genestealers attacks, chipping away at blip piles and paralyzing swarms may be less thrilling, but is probably more forgiving when something goes wrong than just trying to blast your way through and being overwhelmed when you get a 0 on a critical attack roll.
So, do you prefer to use the more defensive teams like black, green and blue (grey could also be considered defensive with their power field and stealth tactics abilities) or the more offensive teams like orange, yellow and red (purple is a well-rounded team, but could be considered offensive because of the flamer)?
Or do you prefer to mix things up and use well-rounded squads with both firepower and defensive skills?
On a side note, I recently had my first victory in the librarium vault, using black, blue and orange. Lorenzo is a beast!