Casey,
While I can't speak to the difficulty of swapping out your Aqua Hot for an Oasis I can speak to the Oasis brand. My experience with AH units in my first two Beavers was less than stellar in spite of regular annual maintenance. My current coach, a Newmar, came with the Oasis unit. I have had this coach for almost 8 years and have had little problem with the it with only minimal maintenance. So, if the conversion isn't too complicated, I would vote for the Oasis. Good luck with your decision.
Tim