I use the HDD , the trick is not to hard mount the unit , put it in a paded bag and and wrap it around rollcage, seat, what ever you can , but have it dangling.
Brad
"how does it compare with the POV kit on quality, ease of use? spec? it's pretty close on price"
quality is good not far off DVD , very easy to use , soon as you plug in the camera it's ready to record via inline remote which also has the mic in it .