Iris Pro is very good in terms of performance but I wouldn't go so far as to say that it's better than the 650M. It would seem that if you pumped up the resolution and graphics quality in games, the 650M nearly always has the edge over Iris Pro. A good article to check out: http://www.anandtech.com/show/6993/intel-iris-pro-5200-graphics-review-core-i74950hq-tested
That's why I'm wondering if the Iris Pro's only real advantage is less power consumption, not performance. I'm actually considering a refurbished 15 inch with the 650M.