I think the question everyone is trying to answer, and I recently wondered the same, is: by manually shifting an automatic car, does it cause premature wear on the transmission?
It is my understanding the answer is yes, depending. If there are large speed differences between gears, the sudden change from say third to second will cause the transmission to have to "synchronize" rapidly.
Selecting a lower gear to accelerate and shifting manually (as long as one lifts slightly at the up shift) is A LOT less stressful on a trans than the example in the second paragraph.
One reason I like Mercedes (some people don't like this about them) is the rather deliberate transmission functioning. By how much throttle is applied, the transmission will automatically select the appropriate gear for the road speed and load.
'03 E320 Wagon-Sold
'95 E320 Wagon-Went to Ex
'93 190E 2.6-Wrecked
'91 300E-Went to Ex
'65 911 Coupe (#302580)