I use Music XRay a bit and have had limited success. I think mostly the opportunities don't match my style of music much. Lots of Hip Hop stuff on there that I can't submit for.
I have submitted to maybe 10 opportunities (all of which you pay to submit) and from that have 1 song on hold, so nothing from it but waiting to see if the guy can sell it on.
I think it is fine as a service but just don't submit anything unless you really think you have a song that is perfect for the opportunity, is produced and mastered well enough etc. It's really got to be PERFECT!
Personally I might try looking at SongLink or Taxi to see if they are looking for things more my style.
Tom.