Well, I just read through the user manual, and it makes no mention of the "suggested" C value, but given the motor, and it's limits, I'd say 1250 mAH 10C should work just fine!

From experience, it does. The motor does get hot, but nothing that can't be helped by the "heat sink" mod.

You can hear the head speed decrease when the charge starts getting low, so as soon as I hear that, I bring her down, let her cool off, and then re-charge.

If anyone else can think of why this battery is not good, let us all know!