A couple of years ago I booked an AY flight to HEL in J on their A350 via one of the OTA's (I believe Travel up). It was one of those daft looking fares where OTA was about £220, booking via BA was about £500, and direct with AY was about £700.
I always got the impression that if you just book and fly then OTA's are ok, but if anything changes it can be difficult to get things sorted.