Just ordered the Lantiseptic from Amazon and tried it for the first time today, on a 35+ mile ride, and seemed to work a treat. You are right about the spackle part though, and it is quite interesting to get the stuff washed off your hands.
It does NOT easily rinse off with soap and water, but that makes me think it will last longer on the chamois and won't sweat off after a few hours. We will be riding two more longer rides this week, so it will be interesting to see how it does again.
Thanks for the tip!
"Don't go too fast, but I go pretty far"