Quick follow up b/c NC2WA requested.
I ended up getting a full UST Racing Ralph for the back, and UST Rocket Ron for the front, mostly because I have a full UST rim and I really just wanted a system that's light, works reliably, can be changed the day before a race and wasn’t going to leak, and wasn't going to be gaining weight all summer while the Stans sealant was drying and needing replacement.
This is my first tubeless tire set up, and they certainly do ride great. Running the front at 30 psi, the back at 32 psi and they ride like there is much lower pressure in the tire, but don't have any casing squirm. Really happy with the ride characteristics. Went over a rock garden and heard my rim pinch the tire, but haven't seen signs of a pinch flat, so I guess they're fairly robust.
Tires were a total PIA to mount initially. Lots of cussing and I broke two tire levers. Once mounted, pressurized, and stretched out, I can get them on and off by hand and it's no longer an issue.
The tires aren't really fully air tight without tire sealant. Mine were going flat within 24 hr when run dry (side walls leak). Consequently, I squired a heck of a lot of Slime tire sealant into the tires on initial set up; tires sealed up great, but felt slow on my first few rides. Took out the extra sealant, and measured out 2 oz of slime for the second install and the tires became a lot easier to peddle.
The Racing Ralph truly is only for dry conditions. I thought they would perform well in slightly damp spring conditions, and I was mistaken. The RaRA packed with wet sand and wet dirt at every opportunity, compromising traction. By damp I mean you can see an imprint of your tires center tred in the dirt after you roll through, this is by no means mud. Rocket Ron did great in these mixed conditions and had no packing up issues.
The tires never felt like the rocket ships I was hoping they would be. Maybe my expectations were too high, could be the weight of the UST tire, could be damp trails, could be spring time legs, don't know. The ride is great, the reliability looks to be good so far, and dry traction is excellent. I may be looking for a second RoRo for the back to better handle mixed conditions.
Hope this helps.