I have found it a bit amusing that the orig factory disc brakes (Chrysler and Corvette) were 4-piston caliper units. Yet they were known to be troublesome and expensive to fix, back then. Then, the single-piston caliper came out and everybody was pleased with how much simpler they were to rebuild and how well they lasted. Seems like Corvette never did go that direction, so expensive rebuilds were just a part of the Corvette culture, it seemed. With the most costly Corvette rebuilds including NEW caliper halves, until the stainless steel sleeve operations came to be popular.
Then, as vehicle speeds and such started to increase, brake performance had to increase, too. So the 6-piston caliper was born, for MORE clamping force AND a more uniform clamping force of the pads to the rotors. Which tends to validate the reason for the multi-piston calipers in the first place.
Stainless steel sleeves for the caliper pistons plus syn brake fluid should make them last a lot longer, I suspect, but at a price.
Scarebird's items look interesting and neat. Just check back periodically to see IF the parts used might have changed. Depending upon IF the auto supply source for rebuildable items might have changed! I like their orientation of using OEM-validated/produced parts, BUT what they might use might have a supply which "dries up" as time progresses, by observation.
I suspect that for general use, or even HD use, the single-piston caliper disc brakes can work well, especially with HD metallic pads. So, no real need to chase the earlier items unless that's what you might desire. IF you might desire to go with the earlier items, I might suggest the stainless steel sleeve operation and good syn brake fluid to help decrease the latent moisture collection and related corrosion situation, for good measure. Not unlike what the Corvette people found out long ago. Which THEN makes the "big deals" finding some good rotors and a rebuildable correct booster.
Just some thoughts and observations,