There are vast differences between the breathability of wader material.
I'm sure you could find a difference with proper measuring devices. But for all intents and purposes, no. All of the breathable materials on the market these days are excellent.
As well, one must consider durability measured in abrasion resistance as well as puncture resistance of the material used in waders.
Function of the surface coat and thickness, not the breathable layer. But I'll admit that's usually packaged with the breathable layer as a complete fabric. This is probably the real difference between Gore Tex, Dry Plus, and all the others.
And again, I am indeed taking longevity into account. If you pay twice as much for a thicker layer, and it only lasts 1.5x as long, it wasn't worth it.
Also some waders have seams that sewn and taped while others are welded.
Realistically the biggest difference between waders is in durability of the fabric and the seams. I am taking into account durability. Nonetheless, see above. If you pay twice as much for seams and workmanship that will last 1.5x as long, it wasn't worth it.
It's not measured purely in hours of useful life. It's measured in dollars per hour of useful life.
What about DWR (durable water repellent) which one is used, how is it applied, surface or using Chemical Vapor Deposition (CVD) machinery? How effective is it new and how long will it last?
There are differences but the best won't go much beyond a year or two. To maximize life of any of them, you have to re-apply yourself.
How about features, like pockets where you want them, waterproof compartments, zippers, waders that fold down to waist-highs for the warm weather, etc.?
This is me personally, not you. But everyone puts pockets in the chest. Chest pockets are nearly useless for me. The zipper is kinda cool, but I won't pay an extra $100 to make it slightly easier to take a leak. I'd rather spend the extra 30 seconds.
I do like waders that convert easily. For what it's worth, the best pair I ever owned in this regard was a $75 pair of Hodgeman's, the the Orvis Silver Labels were nice as well. Nearly identical design. The Hodgeman's were a bit thinner which made the fold down a little easier.