The EZ clip system is a legacy Aeroquip product and has been around for about 25 years. I'm the test lab manager for Danfoss Power Solutions Fluid Conveyance Group and have been involved in the development and testing of this product line since its inception. As far as the robustness of the EZ clip connection, it is as robust and leak proof as a factory crimp connection. It meets the same burst, impulse, moisture ingression, permeation and coupling integrity (leakage at the fitting) requirements as the crimped connection. SAE requires the coupling integrity test for all AC hoses to go through what they call 4 cycles which are alternating hot/cold and hot cycle...which account for 2 cycles...and you do that twice. We qualify the EZ clip fittings with our GH001 hose to 6 total cycles.
To address the robustness of the thin vs thick hose. The GH001 hose used with EZ clip is a veneer style hose with a proprietary veneer layer. You can actually kink the hose and it will not affect the integrity of the hose (although its not recommended practice to kink it), the reinforcement is PVA filament which is 3x higher in tensile strength as the Polyester filament used in the thicker hose...which allows us to make the reinforcement package smaller in diameter. The thicker hose is a barrier layer which uses a much thicker layer of material to resist permeation. It also has a thicker innertube, thicker cover and a thicker reinforcement package. Do not kink the thicker hose as the barrier layer will weaken and develop a leak path. We also manufacture the thicker hose as it is a little lower cost to produce and some customers prefer it (because that's what they have grown up on), but the thinner GH001 hose is actually a premium product with a little better performance that we also supply to a lot of OEM's with crimp fittings.
Ugliness....well I can't argue that it is the prettiest fitting out there, but for the ease of use you can't beat it. We pioneered this style of fitting and there are several out there that have tried to duplicate it....but none have matched it's performance. The barrel crimp fittings aren't the prettiest ones in the world either, and they are extremely sensitive to the crimp location to make them work properly. That GH001 EZ clip cage with the grooves in it will properly locate the clips every time so the end user makes a proper assembly time and time again. We do offer -4,-6,-8,-10, -12 and -16 size GH001 hose with the EZ clip system...the larger sizes being suction side and the smaller sizes being pressure side.
Vintage Air has been our customer for as nearly as long as the EZ clip system has been around. He isn't lying that it "works". It has a proven track record and I'm glad to see someone independently bragging up the product. You could probably source EZ clip fittings and GH001 hose from Aeroquip distributors....but since Vintage Air makes AC their business...they probably stock a more comprehensive variety of fittings for a similar price to the Aeroquip distributors.