Dooglus is a reputed member of this forum.

He found a bug in your site, whether he is a competitor or not, he found a bug which could have lost you a few btc. If the same system was there for "Free play" too, then many would have spotted it and if you were unlucky could have cost you losses.

He has helped a lot of sites recently. like SD.

And there is no use paying for a review unless it is for a very reputed site which will affect the traffic considerable, which I doubt is the case.