Mark,
It really depends on your out of pocket cost. If it only cost you for the tables, then you are in a winning spot. Everything after that is all profit for you. On the other hand, if you have to pay for rental space, you may be pressed to make enough to pay it. If you get to keep a % of the tables, plus a % of the food, the only cost you will have to recoup is the cost of the tables, plus the vendor licensing fee the city charges for each table, which probably isn't much in Gilbert.
The smart choice would be to go with Diamond Tables i would think. I like both, but personally, i think the Diamond is much more durable, easier to move, and will probably hold it value. The GC definately holds it's value too. As you know, many tourneys are going to Diamonds now.
Just my $.02. Hope it all works out for you, i'm all for more Diamonds in the valley of the sun.
Dennis