I completed the 4-piston upgrade this weekend. So far I'm impressed with the performance, though not able to thrash it much yet. Since we also replaced the rear differential at the same time, I'll need to complete the break-in before I see how it works for trailering. For the cost, I say it's well worth the investment. I cannot comment on comparisons to Brembo, Wilwood, Baer, or other big brake upgrades, because I've never had any of those. Here are some observations:
It was actually one of the easiest upgrades to do.
The whole installation took about 2 hours, which included replacing the brake lines and bleeding the system. That's with an assistant for the bleeding. This assumes you've test fitted your wheel and there are no clearance issues. I had already spent another three hours ahead of that smoothing the calipers and painting them.
I did go with R1 Concepts drilled and slotted rotors and their Optimum OE pads. I doubt that adds much beyond stock braking performance, but I've had better success with d&s rotors when it comes to warping from heat. The set I took off had 130k miles and had never been turned and were still running true.
The only tricky part is getting the calipers centered. One standard washer was not enough, and two were too much. We scouted around and found some thinner washers and put 1 thick washer and 1 thin one. That was perfect. So if you do this, have an assortment of 1/2" washers of varying thickness on-hand to try.
I'll post more later, once I have used them for a while under varying conditions. I won't mess around with measuring stopping distance, but I will post my review based on my driving experience compared with the previous 214,000 miles with the stock brakes.