Latex gets you a couple watts per tire. And maybe 5 seconds on a TT. Could be the difference from Podium to top 10 but not something that can be measured comparing times week to week. The quickest way to compare would be a slow rolldown test performed multiple times on the same day in calm conditions and only change the tubes, all else identical. The latex tubes will rollout further every single time. To quantify in Crr takes more effort but it can be done, too.