Well done - and thanks for the report.
Why 'well done'? Because you didn't leave your critical facilities at home when you went to OAT. As you suggest, OAT's Open Day is a marketing exercise structured to make the prospective student feel privileged to be there. It's no accident that it's very similar to the induction days within the military and other large employers - but the difference is that you are paying them, not the other way round!
OAT's marketing is slick. It has to be; they want a lot more money out of you than most FTOs, and they need a lot of you. But they are a business, there to make money - and some of that money may well come to them from the airlines they send graduates to. In other words, their sales product is not only their training system, it is their graduates - though not to the extent it is with CTC.
Nevertheless, you are the paying customer and if what you see doesn't float your boat (or is outside your realistic budget) remember there are plenty of credible options. Oxford is a very good school, but it's not the only one. As some airlines boast, 'we always remember you have a choice'!
Scroggs