Ryan will probably put up decent numbers, but I would want to have a very solid backup that matches well on bad matchups for ATL.
I am NOT a fan of QB/WR combos. I have been burnt time and time again over the 15+ years I have been playing. The only ones I could conceive of this year would be Moss/Brady, and I suppose a case can be made for Manning/Wayne, but not Schaub/AJ. Last year maybe... if you had Rosenfels on your squad as well. But this year, if (when??) Schaub gets hurt, Sage is gone and now you have a HUGE dropoff in talent at QB... making 2 players on your squad worthless.
So all that being said I would say Ryan over Schaub for your squad, especially if it's a keeper league.
Please take a look at mine: viewtopic.php?t=438527
Thanks and Good luck!