Some of the links on this forum allow SMF, at no cost to you, to earn a small commission when you click through and make a purchase. Let me know if you have any questions about this.
Might have trouble fitting 2 grills inside unless an ECB or some other dome lid fits over the top. Otherwise, I think its a great idea for a small smoker (too small for my family, but we like to cook enough food to last a week or so once we get rolling). Same amount of work for one meal as 4-6 meals, right?
If I might add something....there is a somewhat crucial dimension when building a UDS, and that is the distance from the bottom of the charcoal basket to the first cooking grate, it is 24" any closer than it may get too hot at the cooking grate level. If you can maintain that distance in your 30 gal. build you should be okay. Good luck with your build and don't forget the que view.
Coffee junkie is right about the distance thing....another thing you could do is to build it similar to the ecb gourmet, and have a water/sand pan above the coals to act as a baffle so it will be indirect heat reaching your food....that way you could have two cooking grates to be able to handle more food. The heavier metal of the drum will help keep temps more stable, too!