First of all, pc users have been copying and saving photos (and most other data) to cd's and dvd's for over 25 years. It works fine. And if the burn process fails you'll know right away and you can redo it. There is zero risk.
By the way, I guess I've been lucky but in all the years I've been using cd's and dvd's as backup media (and this goes back to the mid '80s when they were first introduced) I've had fewer than a handful of burn failures. If you use name brand media, handle them properly, and take your time you are less likely to run into trouble (though it's bound to happen once or twice regardless).