17-55 IS, there isn't an EF lens that matches it and it is a great portrait lens....
And the 7D has spot point AF which is actually quite nice for portraits too.
Battery life is many times better than the 5D, so less time taken up changing batteries.
You did ask for some advantages, I can't really come up with too much more.
And you are really stretching it when you are claiming the above points are advantages. I get by quite well with my 85 1.8 lens for portraits thank you. As far as battery life goes, I've never run out shooting portraits with the 5D. If I did, it takes what 20 seconds to change batteries. Never had any issues at all focusing the 5D for portraits.
I don't believe any of those points you detailed are advantages.