I'll take a stab at this. I have the Brinkmann trailmaster horizontal, similar to the OKJ you are looking at.
I average 12lbs of charcoal, lump an briquets, four 3x12" pieces of oak, and five to six fist sized pieces of hickory each smoke.
There are times I can't get the temp low enough, there are times I can't get it to keep heat. I've made many mods and sealed it well, but if I'm not watching it every 30min, no idea where it will be.
I don't mind smoking on it, but as much fuel as it burns I feel I have to make each run count. (Money is tight here) So I'm not going to fire it up for a single brisket, I'm not going to do jut two slabs of ribs, I feel I need to fill it and cook a lot. But with a family of three, honestly I'm looking for something smaller and more fuel efficient.
For entertaining, buddy is coming over to watch the race and help with 12-15 people coming later, it's great and I love it for that! Three slabs of ribs, a chicken and a medium sized brisket will fit. But day in and out, it's a pain to prep and cook a weeks worth of food for the three of us in one smoke.
Just my $.02, take it for what you paid.