I first tried the 303 Firecrests and hated them but I may have gotten a bad wheelset as they were very twitchy over 20mph in any crosswinds. I then tried the Enve 4.5 ARs but my tires were consistently losing a lot of air quickly, even with Enve tires. Overall, they held speed great and were comfortable with a 28/30 combo.
I then got the 454s to try. I dropped the PSI 2 more than Zipp's calculator and they are close to the comfort of the Enve's but they corner much better and they hold speed as well or better. They biggest difference is faster engagement and they climb better - things I didn't know I was missing out on with the Enve's.