Although we've not cooked on either, we had a chance to talk for a good while with George at the Decatur, AL comp. We are currently using a CTO for vending and larger cooks for catering. We're really considering swapping it out for a Vault for more capacity and the ability to NOT need electricity if we don't have to have it.
We haven't considered the Sniper, but only because we already have a Jambo for competing and burning sticks.
George showed us around the vault a good bit and we really like the construction, capacity, efficiency and versatility. PLUS....they can have one ready in 4-6 weeks.
I guess it really comes down to what you plan to use it for. It's been my experience that stick burners, although sometimes larger, have some "unusable" space due to hot or cool spots. Yes, sometimes these areas can be put to good use, but if you plan to load it up to do a large cook, you'll have some issues (at least I did when I loaded the Jambo to the gills). The vault, on the other hand, should be more consistent throughout and if needed, every square inch can be used.
My $0.02, FWIW.
18.5", 22.5" OTS
Large BGE (chambersuac's)
The Fiery Furnace (chambersuac's)
Big JT's Smokin' BBQ Competition Team