You want unbiased opinions based on experience. Here we go.
I have never bought a full ARH kit with spring guides and all, but I have probably installed a dozen of their springs and piston seals in miscellaneous variants of the Chinese B19 springer.
I have never fabbed a spring guide nor shimmed one. Using only an ARH spring, ARH tar, ARH moly, and ARH piston seal and occasionally a shim of dental floss to the breech seal. I did the standard de-bur and lube tune to many of these Chicom guns and every single one cocked and shot smoother and with better accuracy. One of them I literally ran
500-1000 shots per week on it and never harmed the spring. That was an E3650 in a Stoeger X10 and one of the sweetest springers I have shot. On another one, an X20S, I put a Tarantula spring in it and experimented using pennies and other misc. coins for piston slugs to add weight and spacing. Up to the point of coil bind that I could not even cock it before backing down.
I learned two things. Maccari springs 1. make everything better and 2. are made to last.
My experience with Vortek, I have installed one PG2 sub-12 tune kit in a RWS 34. Definitely a big improvement there. I bought a Ruger Air Magnum with a Vortek HO Diana 350 spring, not a full kit though. Bought used, he had clipped a coil. Gun was pretty smooth and accurate for a magnum, and about 19 fpe. I received a MM-tuned XS28M in .25 for Christmas from my mom. That one had a Vortek HO spring but otherwise factory parts with some MMM added (Mike Melick Magic). That gun put out nealry 27 FPE with JSB Kings and was the only gun I shot or hunted with for probably 3 years, I could knock the cap off a Gatorade bottle at 40 yards every time with that thing. Or center punch it and blow it wide open if I preferred lol. Killed a lot of critters, even armadillos, with that rifle.
I sold the XS28, the man that bought it told me the spring had broken. So I don’t know.
Some say the Vortek springs are tempered a little too hard and break easier. I think that as long as you’re not trying to attain max power in your springer then you are probably not going to break springs. And if you go for max power or if you like to shoot heavy pellets, you’re going to go through a lot of springs.
Your mileage may vary lol.
edit- one last thing. I deburred a Walther Talon Mag .25 and installed only a ARH piston seal and then a shim of dental floss to the breech seal, honed the compression tube to 400 grit, and lubed very lightly with pure white lithium grease and nothing else. No tar, no moly. Transformed a very twangy changy 26 fpe rifle to a fairly smooth but slightly buzzy 34 fpe rifle with no other special work.
So, your mileage may vary.