We just rode it last week, on two different occasions (different days). I don't know if they had made changes both of the days we went on it, but nobody got wet. Nobody. We were puzzled, as we've been on it many times and the people going backward down the big drop always get completely soaked. The first time we rode it, it was hot and sunny. My wife and I went down backwards and were ready for the big splash. Nothing...nada. Disappointing to say the least. Thankfully people were standing at the elephants and got us wet.
But yes, if the ride functions as it has in the past, you will be wet for a really long time. Probably not 4 hours, but I'd say a solid 2.