Hi, Denny. I can't even begin to imagine why anybody would shoot at a lower bit depth than the camera can give him. I don't know whether or not there's a speed difference between 12 and 14 bits, but if you have a speed problem why are you shooting with a 36 megapixel camera?
Speaking of speed, the other advantage of lossless compression is that it takes less time to do the compression than to write the extra data in an uncompressed file to the card. Things that happen in memory are happening an order of magnitude faster than things that involve storage.