I’ve never raced a 29er with a number on, I have however nailed a couple around one of my test loops.
Possibly worth 90 seconds per hour on a XC course, not totally convinced, quicker yes, worth the money when you’ve already got a 20lb 26er, nah not at the moment.
However since my two previous Trek frames have cracked and they no longer so a 26er SSL, then maybe sometime soon…..