I've got a Southern Pride - though I don't have a restaurant or do catering (it's a long story...). I love it.
Compared to my backyard smokers it is way more than just the name (and way more $$$). My SP (SPX-300) can roll with a LOT of food without increasing cook time. If you use propane in addition to wood it will maintain temps automatically. I always use propane because it fires up the wood, but I've seen some people use wood only and it will work (but takes more effort on your part). The racks are on a rotisserie system so you don't have to worry about hot spots and food placement. There is a fan that automatically circulates the smoke during smoking, and a smoke extractor damper (upgrade) that kicks in to vent outside when you open the door to prevent a rush of smoke into your restaurant or your face!
The stainless steel racks (upgrade) fit in large restaurant sinks (>24" deep and >30" wide per section, not the smaller ones divided into 3 zones for wash, rinse, disinfect). We can put 2 per layer (front and back), so we fit all 12 racks in one sink to add degreaser and let it soak for a while for easy cleanup. Very easy to clean the main smoker with a pressure washer or hose and some degreaser. Bottom is angled to channel grease and water runoff down a drain that exits to the bottom and side of the smoker so you can use a 5-gallon bucket to catch. Circulation fan is easy to pull out and degrease (say once per month depending on how much you cook and how much creosote).
It really is all stainless. Mine stays outside unfortunately and no rust or anything. Still looks great.
I've never used an Ole Hickory so I can't compare. My guess is most commercial smokers have similar features.
I looked at a Myron Mixon MMS-750, which seems comparable to the SP-700. A few items, one it is $4.5K more ($32K versus SPK-500 $27.5K). It's a powder coat paint finish versus stainless steel on the outside (the cook chamber inside is stainless steel for both). MMS uses a waterpan - which is sort of a MM thing. The MMS website spins not having a fan as a good feature (less maintenance), but that means the smoke doesn't circulate as much. Same cook area (sq inches of rack space) for both.
I didn't see an option for a smoke damper for the MMS, but the MMS website doesn't give you much info. The Southern Pride site gives you tons of info on everything. The MMS smokers site says "If you have questions, fill in the form or call." I don't like it when sites hide behind a form or call, but you may be OK with that.
