They say it's more affordable which makes me feel like it isn't as secure as a 1750. I have no experience with the storm series, but I do like the latches, which I believe it said were on the Vault series.
Vault is Polyethylene and has internal dimensions of 50"x10"x6". Not rated to be watertight. Temp rating of -10F to 140F. Not great for a car trunk in the desert or a Phoenix/Badistan airport tarmac.
1750 is Polypropylene and has internal dimensions of 50.5"x13.5"x5.25" Rated to be watertight. Temp rating of -40F to 210F
Vault is just over 9 lbs lighter but lacks the wheels of the 1750.
They both have metal reinforced hasps/padlock eyelets.
The lack of wheels on the long case is a deal breaker for me everything else considerered. I've been using the Storm 3300 long cases when I fly and quite like them. I have some with custom foam and one empty which I put a rifle in a drag bag inside. The case always weighing close to 50 lds and the wheels make walking around with them in the airport/rental car lot etc. MUCH easier. I also like the Storm latches better than the Pelican latches. We use Pelican cases at work and the Storms are easier to get open and seem to withstand abuse better.
edit -- after a little more looking, I see some of the cases do have wheels but just the shorter long case. No prices are listed so really can't tell the "value" these cases provide. Not really seeing anything that would make me want to switch from Storm.
Several models have prices at midway, which shows ‘street value’. I too prefer the storm models vs the original pelicans, but I handled the vault version in the store today and they are quite nice. For $200 for the wheeled model looks like a great option. The buckles work very nicely and are shrouded/protected with what appears to be a very robust design.