Just saw this new variation of the RC500S on their website. The only change, other than the obvious 1channel vs 2, is that recording can be at 60fps, instead of 30. Also, there is the option to add a rear camera which turns it into a regular 500S. Wonder if it retains the 60fps when adding the rear camera? If so, it might make more sense to buy a rear camera with the 1ch, rather than buy the 2ch, if price is reasonable.
http://www.dod-tec.com/index.php/product/detail/118
http://www.dod-tec.com/index.php/product/detail/118