The high pitched whining sound you experienced with your first unit is an obvious sign of transmission failure.
Does the transmission only shift jerky from 1-2 going at low speeds, and at very low RPM? Try using more throttle and see if it still stumbles during that shift. Also, try using manual mode as well.
Sounds to me like the transmission just needs to be reflashed which the dealer could do easily. Could also need a solenoid replacement which sounds less likely, but is possible.
Not just at low speeds, but more noticeable. It seems like I have to give it constant throttle throughout 1st gear until it shifts to 2nd then I can proceed to give it more throttle. If I change the throttle while still in 1st gear, that is when I notice that the hesitations/jerks occur.
Basically I can go as slow as I want or as fast as I want but I have to keep the throttle constant throughout 1st gear.