More testing: With C-RAW, 1.6 crop factor, and electronic shutter, I got 306 shots in 15 seconds before the buffer filled. I kept the button down and the shutter paused for 3 seconds, then resumed shooting for 4 seconds, in a repetitive cycle. After 30 seconds, I had 481 images.

I know that most people really don't shoot this way, but there are definitely times that I do, and those times are always the most exciting moments in wildlife photography. So this has been a good exercise in finding out what the best mode would be that can allow continuous unlimited shooting. The answer for me is 9 fps in C-RAW, and that will now be my default unless I am going birding.