Can't say much about Tripsta and Gotogate, but I don't understand why you call Opodo "obscure". It was founded by a consortium of 9 major airlines and it recently merged with other on-line TAs, forming a mega shop. At any rate, you'll earn exactly what A3 promises for the ticket/fare class combination you bought.

As for the prices, I've never found any ticket which was 30% cheaper than what's offered in airlines' home pages. If i had, i would have grabbed it!