@BrentWhitfield agreed that body weight, terrain, and rider aggressiveness contribute to the variability of nosedives. Other factors such as wind gusts and overbent knees can also play a role. I watched @kbern 's post and although you don't see it, you can hear the nosedive coming. You don't see it because he fights pushback really well and as a result the nose doesn't tilt back, but you can hear that sound from the motor, and that's the sound of the board telling you it's reached its max capacity (at which point you're essentially coasting). With more experience, it's that sound- and the accompanying feeling- that becomes the clue you're about to nosedive. I've been riding for 2 years and most of my painful nosedives happened during the first 6 months as I was becoming one with the board. I still nosedive on occasion, but now, most of the time I'm able to run it out. There's always a possibility there's a malfunction with the board, footpads, etc that triggers a nosedive, but most of the time it's 'rider error' and making that one small adjustment fixes it. As for why there's pushback, FM is limiting the top speed of board and pushback at a lower speed is the warning that you're approaching the limit. I like your idea of getting rid of pushback in favor of a rider warning, but there may be liability issues that are guiding FMs decisions, so they may prefer a more 'active braking' approach.
Thanks for the detailed feedback. I went back to the video footage and listened with headphones and I can hear what you are talking about. I have a couple of questions for you. You mentioned that now that you know better, it still happens, but you are able to run it out. Is that because you are are hearing the noise, then slowing down before nosedive, or are you just able to get your legs moving because of the warning sound? I'm was hoping I could hear the noise and correct in time before failure/nosedive. In other words, I am wondering if once you hear the noise, can you lean back and slow down to avoid nose dive?