Comments to some of your requests. Most of your G9 specific requests are generic to all cameras, btw.
* Allow user to specify EXIF fields like "Artist Name", "Author", besides just "Owner's Name". Others have been proposed. Perhaps someone could collect these and make a separate "EXIF tags we'd like to see" thread.
At least customized RAW Exif or Exif to separate file are being worked on.
* For shooting video: please, oh please display the length of time remaining while shooting. Currently the camera doesn't tell you. So you end up unexpectedly filling the card.
Implemented in the juciphox build.
* Support the display of externally processed JPGs. Currently it throws an error ("Unidentified Image")
Not something that many people find necessary. Very likely requires a complete 3rd party jpeg decoder implementation. A lot of work and is probably going to be very slow as at least JPEG encoding is done in hardware.
* A user selectable feature to automatically disable image stabilization for time exposures longer than
Implemented for some cameras, exists at least in ewavrs private a710 build.
* Remove restrictions on the length of videos and audio recordings.
Video length restriction is a file size issue, otherwise already removed I suppose? I have no idea about audio things, A series record quality is too crappy me to care about it.
* Display histogram of frequency information (sharpness) and translate to equivalent megapixel rating. In real-time (ideally) and/or playback mode. This will make it easy to determine how sharp an image is. And determine the "best shot" from a group of shots (what I call the "lucky method"). Others have proposed merely comparing JPG file sizes to determine "best shot". But comparing histograms is superior since it's the high frequencies that matter.
* Use false color to indicate sharpness. Same idea as the zebra pattern for exposure. This allows a relatively low resolution LCD to tell you exactly which areas are in-focus (or not).
These are likely too much processing to do real time in-camera. Best-shot-selector from sharpness by selecting the largest JPEG has already been implemented, don't remember if it's in any build yet. It really is better than comparing histograms since it doesn't take any time and it's likely just as accurate when there really is a bad shot among the good (or vice-versa). I believe the high frequencies increase the file size the most, after all?
Wouldn't an out-of-focus zebra color most of the scene as out of focus, because there is no detail in smooth surfaces like the sky?
* Ability to shut off LCD backlight. This will extend battery life for shooting lengthy videos on tripod (or audio) like concerts, weddings, etc. With the G9 the Display button indeed shuts it off but NOT in video mode, sadly.
Implemented for some cameras at least in Dataghost's dev build. Btw, AFAIK the display button normally shuts down the LCD (and it's backlight) and the sensor, which both give power savings. Video obviously needs the sensor enabled at all times, which is why the button doesn't work in video mode.
* Improve the playback display to show more EXIF tags (all?).
There's not much room to add OSD in the playback mode that shows some exif. This should probably be a separate exif browser or separate exif OSD for the full-screen view. In any case there's too many exif tags to fit on screen in one page so it will always be a subset. And one must note values must be dug from MakerNotes because of CHDK overrides.
* Support external USB peripherals such as an external GPS device for location-based EXIF tags. A hardware bridge may not be required since most Canon cameras can connect to printers directly. This would imply the USB port can be configured as both a host and peripheral.
USB is a big unknown. There are tons of camera functions related to USB and it's all pretty complicated without any API or hardware documentation. So, nobody's figured out how to work the USB yet. We only have some remote control things now.
* An integrated automatic bracketing and stacking algorithm. Would automatically align frames and stack (using the RAW image mixing modes). It would retain the originals.
* Automatic removal of lens distortion/aberrations (ie, barrel, pincushion, etc) using the actual transfer function of that model of camera. OK, maybe this is asking too much!
In my opinion, all this is better done off-camera because of the superior processing power. But without align, we already have RAW average and some other operations have at least been tested if not implemented in builds.
* Software to make the camera into a dedicated electronic range finder. The focusing system which give the range of different AF points in the scene. Wouldn't necessarily have to function as a camera in that mode.
We already have the DoF calculator OSD. Don't know if we can do much better.
* Auto leveling feature which would rotate shots so they're aligned properly. Alternatives would include artificial horizon (semi-automated) or post processing so you could manually rotate to align to a grid. Practicality would depend on the accuracy of the camera's accelerometers.
Not accurate enough I think (there are threads about IS you can research). And arbitrary angle rotating is again something that I think is best done out-of-camera. The rotation angle should just be marked in a tag.
* Support RAW in all shooting modes. Currently Canon only supports RAW in a few modes.
CHDK always writes RAW on any camera in any mode (except movie) if you want it to. But it's not Canon's RAW. There is no white balance information or any other headers. Improvements for CHDK RAW writing are being worked on.
* Remember ALL settings when powering off. Like Macro mode, for example. This could be a menu option called "Remember Macro setting after power down" or similar. In an afternoon of shooting wildflowers I may power
This is a very familiar request.
* Be able to assign more function options to the Shortcut Button. Such as switching lenses, toggling image stabilization, Macro
Don't know about the G series, but in A series this shortcut button is CHDK ALT key. A long press of that button does the original function. CHDK traps the keyboard and even goes to lengths of trouble to make the shortcut do the Canon thing with that long press. I think this should be possible.
* The MF "focus check" feature is great but still not useful enough. It needs to zoom in even more (25% to 50% more). Otherwise you still can't quite tell if the image is sufficiently focused, even with a magnifying glass on the LCD.
A familiar request as well. It's been discussed recently too. Further zooming may not be possible due to hardware restrictions, but a larger focus check window might be.
* The panorama feature is currently not very useful IMHO because the images are displayed too small. I've taken hundreds of panoramas with the G9 and usually resort to doing it manually. If the size of the images
The SDM build has some improvements which closely relate to this although I believe it's used for a different purpose there. I'm not sure if it's available in other builds in any flavours, but it certainly could make up a better panorama mode.