Madmole (if not, then it was fataal) stated that you could but that you'd be missing out on the changes to RWG between builds. I'd assume it would affect other things as well but that was what they stated. The main issue with continuing a save is that you may have bugs due to changes made during experimental. However, that isn't a guarantee. Even with the update today, the game works fine if you continue the game and just give yourself the missing XP and magazines and such. But you do risk bugs that way. And, like SylenThunder said, using an older save is going to make bug reporting problematic as you can't verify if the bug is an actual bug or only due to your old save.