My wife and I got a 'welcome to the neighborhood' coupon from Graziano's a year ago which was for 2 free medium pizzas and 2 drinks. The pizza was surprisingly decent, and we ate all of it in one sitting. Thin/chewy crust, decent sauce, no canned toppings. I had semi-low expectations when we walked because there were a bunch of 6-year-olds running laps around the place - half of the restaurant is a Chuck-E-Cheese style game room. The restaurant side was peaceful enough to have a conversation.
Saw pictures on the wall of the 10-pound, 2-person pizza eating contest contestants and the big pizza itself, and the whole time I was eating our 2 free pizzas I was feeling pretty confident that I would be able polish off half of the contest pizza.
A few months ago we were driving back from LA and stopped off of the I-10 to grab a quick dinner and ended up at a pizza place in Beaumont, CA, that was formerly a Graziano's. From the looks, taste and texture of the pizza, it was clear that the new owners kept the old Graziano's recipe. We easily ate an entire large pie. IMHO, the best practice for the pizza-eating challenge may be to actually go to Graziano's and try to eat as much pizza as you can during the $5.99 lunch buffet...
Here is a talk thread planning an upcoming Yelp Vs. Graziano's pizza eating contest: http://www.yelp.com/topic/las-vegas-restaurants-with-eating-contests