I can't say I've looked at all the data perfectly - but I would wager that the bridge over the Animas river on the way up to Purgatory was his lowest elevation while hiking. It sits just below 7700 ft, which I believe is lower than any TH he used. Feel free to correct me if I missed another low point!
Andrew/Andrea, this was an incredible feat to follow! Congratulations, and enjoy some well deserved rest! This record seems like one that is simply untouchable. Between the Weminuche Wipeout, the Centennial Elk traverse, the Blanca group and Crestone group days, and everything else - these three weeks have been on another level to follow along with.
I wonder if Andrew has any more insane plans up his sleeve for the future!