Paul,
I have not seen anything in this thread about protecting the motor from over-revving. This is a major concern for protecting the investment of your DC motor.
I know that this function could be done external to the controller through a tachometer monitor with relay to the ignition 'run' switch, but couldn't it also be done in the controller?
Maybe this is outside of KISS but seems like the ATMega8 could monitor a tach input signal and perform the power cut-off too.
What do you think?
Eric