I think that the Canon firmware's choice of bad pixel list is based only on the Canon shutter speed, based on the picture I took where Canon's was less than 1.3'' and CHDK's was something like 32''. For that reason, is it a good idea, when using shutter speed overrides, to have the CHDK bad pixel lists configured? Is CHDK's bad pixel removal done instead of, or in conjunction with Canon's bad pixel removal?
Most cameras have 2 lists, e.g. the SX10, so i guess the SX110 does work with 2 internal badpixel lists, too.
When you override exposure with CHDK, on most (or most newer ?) cameras the Canon exposure value will be set to the nearest Canon value by the original firmware; with overrides > 15s the Canon value is always 15s.
You can also set up the Canon exposure to 15s to make sure the Canon fw uses the correct settings.
When the CHDK DF setting is "AUTO", the camera should use the correct DF behaviour & list...
There are still some issues on some cameras, so you should do some tests to know how your SX110 reacts.
On some cameras you'll get problems when you shoot directly without focusing (half-press shutter) first, e.g. the CHDK overrides may not work correct then or RAW images will not be stored - so you should always focus first, also when shooting night images (use manual focus).
When the CHDK bad pixel removal feature (the one with the badpixel file - not the badpixel.bin for DNG creation) is enabled,
the badpixels from your (CHDK) list will always be "corrected", additionally the Canon firmware always "removes" the bad pixels from the internal fw list.