I did the exact same thing. The esc switch only shuts off the esc, but the servo still gets powers. I ruined 2 Maxamps 6000's, so I decided to put the nitro motor in the car. All I can say is after one cleaning and clutch rebuild, I'm switching back to BL.
It's not just the external BEC/servo, the esc has a certain leakage current inherent as soon as the battery is plugged in.
“The modern astrophysical concept that ascribes the sun’s energy to thermonuclear reactions deep in the solar interior is contradicted by nearly every observable aspect of the sun.” —Ralph E. Juergens