Have a look at "The Beast" in my signature. It is very similar to both the Stockton and MOAB, but still its own pit. I forget the exact measurements of them all, but I think it is larger than the Stockton and smaller than MOAB. I commissioned it to be built before I ever heard of the other two so that it could be both a catering and competition pit. It's outside dimensions are 24" deep by 33" wide, 1/4" thick. The firebox is 24"x24"x24", 1/2" thick. Not small by any strech of the imagination.
The thing is a heavy hoss! When I had it shipped to me, I believe the BOL had it at 1,540 lb, with a steel tube pallet that they built for it. It was originally built as a "backyard" pit, thinking I could move it around...I was wrong. Rolling it on castors was a pain, and I found that loading it up onto a utility trailer was darned near impossible. I actually got it up on two trailers: One took several hours of shinnying up a narrow ramp with the help of a come-along, and the other on a much smaller tilt trailer, I used a winch mounted to the trailer. Got it up there fine and then couldn't right the trailer! If you have more of an enclosed trailer with a sturdy floor, nice ramps, and a winch, it would probably be easier. All of this is to say that it is heavy and trying to move 1,200-ish lb in this form factor can be difficult. That is why I built the trailer upon which it now sits.
The trailer is amazing! We towed this thing to 8 competitions last year and are planning for more this year. The farthest away comp was 250 miles away and over a mountain with 6% grade. We have not had a problem. I really don't want to jinx us, but if you design a good trailer and take the weight of the pit into consideration, it's very possible to tow this thing safely. I'm going to be adding trailer brakes to it in the next few weeks for added safety on a 600 mile trip I plan to take in October ;-) I know YS builds trailer mounted pits, so I'm sure they can handle it, but just think things through with them. My trailer is not a "standard" one.
You asked about how it performs in competitions: I can't help you a ton since my pit is only similar, but but I've been happy with it. There are many pits out there that you can use to compete, each with their own style of cooking and flavour of finished product. Over the last two years I've gone back and forth on things I like and don't like about the pit. It's big and can hold a lot of meat, but it's big and difficult to transport relative to a BWS or Stump's for instance. It's a stick burner (ish) so has great flavour, but it's not insulated, so is some-what more temperamental (and adds to the weight). If I had it all to do over again, I'm sure I would order something different, but isn't that almost always the case?
I hope this helps,