I gotta agree with the majority here - for competition get a pair or more of WSMs or the Brinkmann and a WSM. As the owner of a NBBD (which is very similar to the Brinkmann) I can tell you that trying to cook all four categories on it would be pretty tough. Not impossible, but difficult - you'll be opening the lid a lot and that can be a big problem since there's no insulation in the Smoke n Pit. There are ways around it, like cooking your briskets and butts first and coolering while you do ribs and chicken, but for the $$ I'd do a pair of WSMs that'll give you WAY more flexibility. You can use different types of wood and run them at different temps, etc. The WSM's will be easier to tote around too!
Head Groundskeeper - Squirrel Haven Estate, Lenexa, KS
Chief Cook of the infrequently competitive Fullwood Bros' BBQ Team
Cigar Lounger, Malt Beverage Tester
Owner/Operator of: Superior "Stealth" SS2, Brinkmann "Lefty" Bandera clone (retired), Comalco Black Dog grill, and various Weber kettles.
World's fastest Belgian/Cuban Racing Yellow thermapen.