I have two 2 mode P7, one 5mode P7 and. MS900. Side by side, the MS seem to throw a farther and wider beam but the P7 seem to be slightly brighter because the color of the light from the LED is more pure white.

If you can set up a MS where things like the connector is secure, battery rain drip proof, and not having to constantly removing the MS from your bike, then I recommend the MS only because I run over 30 minutes of lights per day and I cannot stand having to unscrew the P7 to get the battery out to charge everyday. Charging my MS is easier because the battery is permanetly mounted to the bike and the wall outlet is 2 feet away.

Otherwise if you are constantly yanking wires on the MS ( and Heaven forbid ) as "It Just Me" noted, then it will break faster and a P7 might be better for you. One note, as my luck goes, all three of my P7 has loose connection that make them dim by themselves when I hit bumps. A little work can solve most issue with the P7.

For the mode of P7, I prefer my Off-high-low mode over the 5mode. I don't use much of the strobe or SOS a d sometime getting it to the high mode is a hassle when I just want to get going instead of people at the train station watching me flicking switch in the darkness.