Supposedly you have more of a chance to get items for the classes you aren't using it on, at last that's what some believe. And seems true for my wife's plethora of titan and hunter gear from engrams (her being warlock). For me it seems entirely random. I bought 3 and got the titan alpha lupi, lucky raspberry, then the hopf. Of course I've been wanting the hopf for a while now, and the other 2 I didn't have anyway. Got lucky I guess