Straps are good for people that need a chamber that will go to higher pressure who don't want to pay the expense of a non strapped chamber. Straps aren't as convenient as the non strap type but so is paying double or triple the price either. It is a little harder to get in and out alone with the straps.
I will say that the strap type models rarely have any returns due to window leaks or zipper failures. The belts hold all the pressure points off the zippers. Many people don't like straps who want ease of use might have to get their chamber repaired more often and that is an expense worth considering. Most clinics don't mind this because it is much easier to use.
Note: those in the USA don't really need to worry about going over 1.3 ATA because it is not allowed here. The extra safety of the straps and buckles are may be worth it if longevity of the chamber outweighs the extra time it takes to get in and out and fasten the belts and zippers in.
One thing for sure is that the chambers with the belts last longer, especially if the zippers have a low tooth count. Many people are buying straps with buckles and custom making their own chamber so they can go to higher pressure. I hear the worst stories with people doing this because the chamber itself (the welding, etc) has to be able to withstand over 1.3 ATA.
Old school composite buckle straps. I only promote chambers with solid steel buckles. I am tired of companies trying to cut costs.
Note: the only chambers that go to higher pressure (over 1.3 ATA) that don't have straps are the new Teflon chambers. These chambers go to 1.4 ATA. See my Oxynova page.
Other than having the Teflon bladder which is very expensive, the strap/buckle type chambers are the only chambers that can go over 1.3 ATA and still be FDA Cleared. The chambers with straps are much cheaper than the Oxynova type that doesn't have straps, less than half of the price.
This is what newer straps look like. Unlike the old school buckles and straps, current straps now all have metal buckles. No more composites.
Notice the straps are only fitted only to support the zipper and doesn't go around the entire chamber anymore. It is much easier now to get in and out and not have to pull the belts through the loops
No more belt loops.
This is the old style belt chambers.
The latest strap type chamber. Now the straps are less than 1 foot. The new Dive chamber has a reinforced nylon thread so there is no need for straps wrapping around the entire chamber anymore.