I love my retrospective 20, I can't ever see me buying other bags than think tanks. As a shoulder bag it will easily fit what you want, it's deep enough to take a 70-200 attached. I tend to use it with a 17-55 on the body with a couple of primes in the bag, a 600rt speedlight and wireless trigger and have room for loads more stuff. It also has room in the back pouch for an ipad which is great for me 
I might go and look at one of those 7's myself for when I don't want as deep a bag.

I might go and look at one of those 7's myself for when I don't want as deep a bag.