How deep is your tank? I had a 24" Finnex Ray2 DS on my 29G (~16" to substrate) and I measured approximately 65 PAR at the substrate with the light right on top of the tank.
Those things are built like tanks too. I must have dropped it from the top of the tank onto my tile floors 6 times or so, and it never skipped a beat.
I use spot lights on my 30 gallon and they work great but prefer a nicer sleeker look over the tank.
I saw the Finnex Ray on Amazon for only $100 and didn't pay attention to it as thought to inexpensive this was very informative, thanks.