More benchmark goodness for your pleasure;
https://learn.adafruit.com/introducing-the-raspberry-pi-2-model-b/performance-improvements (https://learn.adafruit.com/introducing-the-raspberry-pi-2-model-b/performance-improvements)
The BeagleBone Black is interesting but it just doesn't have enough RAM and neither does the XM either. In any case the XM is over 4x the cost of a Rpi2. Watch this space is the phrase that comes to mind!
All the best
Andy