The max is about 30*, but now using the limit stop bolts it's about 5*. I would think that less teeter the better, up to the point where the differential lift starts to roll the gyro. I'm assuming that the teeter is used to eliminate this rolling motion. If you have too much teeter the gyro will be impossible to roll.

I'm going to use it fixed. I don't think the teetering rotor head is the way to go for a DC gyro, your small inputs would be canceled out by the teetering. I would think that the plate hub of A of A would be the way to go on a DC gyro.