I know a guy who ran a restaurant (Canyon City Barbeque in Azusa) off a big Klose until he could get his Southern Pride delivered and installed. He was a big deal on the KCBS circuit, Memphis in May, RibberFest, all those sorts of comps, plus some serious BBQ catering (or at least as serious as it gets in SoCal) and believe me -- he couldn't wait to switch. Heck, you might as wel go "open pit."
FWIW, the FE (Fast Eddy) and FEC series are pure wood burning -- and to my mind more comp and catering than purely restaurant. I know some people who did very well with (what I think was) an old 100 series Cookshack in a BBQ/soulfood operation (KC BBQ in Venice, CA) for years. But it was a fairly low volume operation.
Yes to the suggestion about looking in on the various BBQ forums and asking around there.
The more I think about the Cookshack, the more I think I'd rather have a rotisserie or convection cooker for any kind of serious BBQ operation. They're a lot more forgiving. Pure cabinet style pits are not perfect. They all have air flow issues -- the more heavily loaded the bigger the issues. This means either rotating the product or improvising cook times on the fly to adjust for load. Convection fans go a long way to solving the problem, but perhaps not as well as rotisserie racks.
If you're thinking of a somewhat portable unit, you might want to contact Backwoods Smokers. They're incredibly good units -- and are blowing away the Cookshacks on the comp circuit.
On the other hand, Cookshacks are really good for holding low, fish-smoking temps. If that's part of what you're thinking of doing, it could be the deal closer.
Lots to think about,