I've owned a vault and now own a Backwoods.
The Pitmaker products are "heirloom" pits. If you don't bang, or scratch your Backwoods you could say that about them as well. However, the difference in the quality of construction is night and day.
the vault weighs in at 925 lbs, you have to go a bit up the food chain in Backwoods to find the same weight and also about 2k more in price.
The vault has plenty of cooking room and you can fit two full size pans on each rack.
My Backwoods is very, very easy to regulate and change temperatures up and down. The vault, was not so much, but I cook dry, I hear it is a different story if you use the water pan. I hear the Safe is much more manageable.
Both good cookers, just depends on your budget and what your trying to do. I had my Vault on a trailer but had intended to get a pop up camper for some comfort so I sold it.