I use the Concept line at work so I'm still with it.The 2042 is fast drying so you can't hose it at all or pile 3 or 4 coats on without trapping solvents,but the slower 2021 is really nice.Air drying it I wait at least 24 hours to sand it to buff or recoat.2042 tends to soak in and die back if you push it in the least,but it's nice to burry tape edges quick and do the final in 2021.Same hardner but just enough difference in chemical makeup they can't be mixed wet.2002 is great but way too slow for scooters.I believe 2002 and 2021 can be mixed to adjust the properties like the previous 2001 and 2020,but it's useless to do on small stuff.The 2021 and 2042 are pretty thick too,too much for my old 2001/2020 MBC to break up nicely.
