If far out I wouldn't book with an OTA as the risk of cancellation or sch. change is too high (and you are likely to be screxxd if occurs because you will not get any assistance from the OTA and the airline willl refuse to deal with you). If on short notice, i.e. the risk of cancellations or sch. changes is smaller, I would go for it due to the significant savings (and pray that you will be able to travel as booked).