I did have some time to play today and checked out most over rides SS, Aperture, ISO, Focus, Quality (SF), and additional display info, DOF Calc, Time, Battery, and Remote control. and many menu functions, DNG, and Raw save incl. the resulting images in PS Elements. All works like my SD990. I did notice the battery voltages were not the same as my SD900 or SD990 that use the same battery??? both my SD's use 3975 - 3425 the S100 has 4050 - 3200
I didn't read the entire thread so I assume all the functionality has already been checked.
I am running firmware 1.01a
Hans
update after running several battery cycles is seems the 4025 and 3425 works for me on my S100 and the SD's using the same type battery