I imagine that a large percentage of OAA students are sold the dream of working for the national flag carrier. BA have taken on 13 so far and I would guess that the year end figure is around 20 - 25 'graduates'.
Would you gamble 25k on a 10% chance of landing a job with BA? Disregarding FR, the next big company to hire from OAA is FlyBe. With all due respect to FlyBe pilots, their FO salary is not as competitive as the likes of EZY, FR etc. You'll need every penny you can get to pay off that 75k of debt.
Personally I'd rather go modular & save 30k+