Hi disneyliz. The only shore excursion more exhilarating than Wild Tours' ATV Adventure would be to take the tour twice in succession!
As far as safety and organization are concerned, the tour guides are competent and the ATVs are well maintained. My DS9 passengered with me. At a couple of points we "flew" into the air and my not-so-little little guy shifted his weight unexpectedly yet we didn't flip (thank goodness). Also, the ATVs are automatic transmission so you can concentrate more on the lack of a paved road - lol.
By all means, go. You'll love it!