hi
thanks to all for all the info. Seems that I should keep the afd. I think my body just needs to be calibrated. It took a hard fall and focus/sharpness has been a problem since. Personally I prefer the ZD mirror lock up which I think is the same as the afd11's.
A lot of times I shoot manual focus, even with the ZD, so focus speed is not really an issue. Will be interesting to see if and when the ZD back arrives and what the price point will be and if it will be an upgrade from the ZD. In any case my thinking would be to get a back with different characteristics to the ZD. Gives one more choice, I suppose.
Thanks Ivan