Interesting and honest report Andy. My own interpretation having driven the Plus Six with same ZF 8HP auto box twice, is that it can provide extremely fast changes but the PCM or whatever controls it in Drive holds on to the higher gears too long then, as you suggest drops several in a dramatic manner reminiscent of early three speed autos on kickdown. Given the far greater torque available from the turbo engines this seems to have got more than a few in trouble. Sounds like the mapping on the Plus Four is similar. Using the paddles in Sport mode gives you far more control.
