I couldn't believe it either at first when I tried the 6d, and I am still wondering if I got it wrong: The fact that Canon forces the *source* files to be deleted is so impudent that it knocks your socks right off... and all reviews I know missed that, they only state "jpeg only" for hdr but don't say that it's impossible to do a custom hdr from raw afterwards in postprocessing and use the in-camera jpeg as a quick preview.NOBODY.. really interested in HDR will do in camera HDR.
I dare to disagree, because there are two types of hdr I do:
* High quality hdr, I'm doing this a lot, often in combination with panorama or focus stacking. For this you just need the raw files, a lot of time and processing power & and end up with all raw sources plus a 100mb+ tif file.
* Quick hdr when I do some walkaround and know there's some higher dr in a static scene than the sensor can take (like the sun/sky/shadow, a reflection, ...) that doesn't require high quality postprocessing. For this I'd find in-camera hdr very useful because as far as I tried it the 6d/5d3 are very good at assembling the shots.
The problem with the 6d here is that you *have* to decide up front if you want to postprocess or do in-camera because it deletes all source files, jpeg as well as raw, and you end up only with a jpeg with known shortcomings in comparison like no way to adjust the wb afterwards. Deleting the source files as an option is ok if you're on holiday and don't want to fill your cards with 7x brackets, but being forced to do so imho is just ridiculous.