I had been experiencing really hard shifts in all drive modes, and especially at starts and stops. I had requested that the dealer service tech check the transmission fluid at the last few service appointments - over a bout a 1.5 year period. The problem continued to worsen.

Last week, I went in and asked again. They continued to tell me that:
a) fluid is in a sealed system
b) fluid doesn't need service or flushing
c) techs don't recommend fooling around with this problem
d) better to leave it alone.

I asked again for them to check. They called about an hour later and said that they checked the level and found it 2 liters low. They added fluid and test drive the car with excellent improvement in automatic transmission function. Then they re-examined the transmission pan and found a hairline crack that was leaking - likely for years. I authorized a pan and filter replacement. The fluid was again topped-off.

My car's transmission now operates as it did at 25,000 miles. Total cost of pan, filter, diagnosis and fluids = approx $500. Very happy with the results.