I've not used the Zipps, so cannot offer any direct experience on that, I did want to try them but found them (at the time) impossible to purchase for less than a billion pounds.
I should stick with them because I have a few sets already. I'm going to swap the wheel out and swap to alu pads to see if it's the caliper that's spongy or the carbon rims are really just shit. It's annoying that the rear (alu) braking is so much better than the front.
I've not used the Zipps, so cannot offer any direct experience on that, I did want to try them but found them (at the time) impossible to purchase for less than a billion pounds.