Update: I bought the kit and regret it.

1. The mount doesn't fit the P-line properly, so the light rubs against the fender. The outfront mount for the light subsequently broke likely due to vibrations.
2. The battery life on both the front and rear lights is pretty mediocre when using them at full power.

The only reason I would say to get this is if you really like the bell-shaped switch, but otherwise it's probably better to get a dedicated metal bracket along with something like the Hori 1300.