I don't have personal experiences with OAT but a number of my neighbors have liked so was considering them for a trip. When I started to research them, I found they did a very DISMAL job in taking care of their clients during Covid. Very difficult to reach, autocratic responses to refunds if you even got a response. Forced rescheduling of tour till following year or loss of payment, etc
Pretty clear that they got a F for their treatment of clients during Covid. If you are considering OAT check reviews beyond their website.
That's certainly true, but I also heard from a number of people that they eventually did the right thing by their customers. It was bad at first but largely because they weren't big enough to handle the financial shock of everything shutting down so suddenly.