Mine actually shifted smoother after the filter change, it was a slight change - but perceivable. The filter was very very dirty, very clogged. I never had the temp light issue - and the job went smoothly, except removing the old gasket from the pan mating surface. (it took a long time). Support the transmission with a jack, drop the crossmember with a socket and a breaker bar, drop the pan, remove the old gasket, change the filter, put a bead of RTV on the mating surface and set the new gasket, then put the pan back on with the new filter installed. Repeat for the second pan, then refill the pan with ~7 quarts of synthetic ATF.

Wash the pans with brake cleaner to remove the metal shavings which inevitably coat the bottom of the inside of the pan.