I have the 3” Rupes and the 21 Big Foot as well. Surprisingly, I still use the HF a lot. I’ve never tried the Flex.I've been through a handful of harbor freight wheels.. for the price they can't be beat. I now have a flex for gel and a rupes for clear. The collonite insulator wax is an oldie but extremely tough to beat too. Jescar plus two coats of 845 has been my go to for years.
Keep it up! It's a sickness.. but love it!