I also only cheat on my main. Been doing it for over a year now, and never even had a scare.
Granted, I don't MSAB. I only AB in the Attic and then use programs for avatars and making neo life less time consuming.
I tried to AB in the main shops on a shell, and did pretty well for a while. Eventually I got greedy, it was frozen, and I lost a couple really nice pets (including an UC darigan.) That's part of the reason I didn't start ABing on my main....