Hi,
I hear what you are saying. I actually record at 1280X920 which is 4:3 aspect ratio to get the widest view possible as I mount the camera about 1 foot off my left shoulder. I then stretch it to 16:9 because I really don't like the black bars on my screen. You are definitely right that it records at a maximum 12,000.
During my testing I found if I produce to 1920X1080 at 15,000-20,000 when I view my videos on youtube at 1280X720 (takes too long and uses too much download to view 1920X1080) I get a better quality. If I upload 1280X720 15,000-20,000 the quality is not as good as the 1920X1080. It seems like youtube produces a better 1280X720 videos when it has a 1920X1080 video to start with.
Now you have to know I am fairly pedantic with the quality of my videos and like to squeeze every drop of quality out of my videos. My old Panasonic TZ7/SZ3 records 1280X720 at 17,000 straight out of the camera.
The thing is with increasing the bit rate you will get a slight increase as long as you don't go overboard. I did do some testing with my TZ7 17,000 footage all the way up to Blu-ray quality of 24,000 and all it really did was make the video huge in mbs.
As I mentioned earlier the biggest tip I have found with Gopro HD video is to use Video enhancement to 1/4-1/2
Cheers
Robert2 S
My youtube channel====> http://www.youtube.com/user/relate2?feature=mhsn