If we will compare only the in-house engine then Qihoo have an edge to Baidu.
If Avira engine both on then Qihoo still on the edge
Then of course Qihoo's 3 main engine when all are turned on surpasses Baidu.
What I'm saying, its a developmental phase for continuous improvements for in-house engine should measure; others are just supporting components.
Now in terms of features, Qihoo already proved that although FP rates are always a drawback, meanwhile Baidu keeps it to be simple and straightforward as possible.