Nothing is being written to the card until you hit the shutter button, it's only using the internal buffer memory for the pre-shot info. I was wondering about that myself and was watching the card activity light when I used it a couple times
I assigned the right button on the D-pad to enable the RAW Burst Mode option so I can enable and disable very quickly as when you hit the button to enable it the menu pops up in the EVF, set the options and save. Same to disable. This nice thing is that it remembers all the previous options when being disabled in terms of shutter mode etc. I was worried it would turn it off but leave it in electronic shutter or something.
I tried the option out a couple times this weekend and found it to be very useable in the right circumstances. Unfortunately I didn't get any shots I wanted to keep as the bird I was focusing on kept fling away from me when it was leaving its perch rather than flying towards me, but it was nice to practice with the option and see it work a bit. I didn't think it was something I was actually going to use when I first read about it
I think you are right. I just tested it and indeed the red LED does not come on while half-pressing the shutter button, even though the little RAW Burst Mode indicator is there. I had tested this before and recall seeing the red LED light on when I checked, but I must have pressed the shutter button down all the way by mistake. This is good.






