Onboard gets my vote everytime. My FlyCam is very versatile but must have ample light, and the resolution is 1.3 MP. I am looking for something like a FlyCam HD, which doesn't exist, although there are a few options I saw on Amazon. And I need a better cam with optical zoom for just shooting air and ground video.
"Should I add a light soundtrack, or would you rather listen to the mosquitoes being killed by the silent assassins?"
That should be determined mostly by the quality and substance of the audio IMO.
Most of the ones I've done have music because there's too much gear noise/wind noise to be worth a crap

But I did one video 50/50 audio to music and that works sometimes too. I have some new ground and air vids with front and rear views mixed up and I'll be posting those soon.
I'd like to see some onboard crawling/low speed chase vids, that's about all I have for ideas at the moment.....