Replaced the batteries on my W124 and R129 w/o the need to reset anything but the radio codes.
Oh yeah, the SL top operation had to be resynchronized, but again, that was an additional 10 minutes over the five minute battery swap...
2009 ML350 (84K) - Family vehicle
2001 CLK430 Cabriolet (71K) - Wife's car
2005 BMW 645CI (124K) - My daily driver
2012 Mustang V6 (60K) - Daughter's car