I had a MULE before moving to an Osprey Talon 11. It was the best move ever. I find that the talon sits on my back much better. I don't feel as though its getting in way as the MULE did. The additional few litres on the talon meant that I didnt need to use a larger bag for winter when carrying extra layers, as i could squeeze all of my kit into the talon at a push.
The raptor has taken many of the features of the talon and added some bits and bobs that would be useful for bikers. Reviews in the walking mags don't rate the raptor due to its distribution of volume, ie pockets for your pump, tubes etc. But they did note that for biking it would be ideal.
I have had three MULES – old and new version as well as a HAWG and Mayhem?
All are long gone and I use osprey talons for both walking and biking. I have the 11, 22 and 33.
Pinkbike on the Osprey Raptor – http://www.pinkbike.com/news/Osprey-Raptor-Pack-parts-check-2010.html
NSMB on the Osprey Raptor – http://www.nsmb.com/3499-osprey-raptor-18-pack