PBSF is as good as anything on the rear until you start spending in the $100 range for just the rear light.

I have a Magicshine and a P7 flashlight up front. They both put out the same light, the difference is that the flashlight is 100% waterproof, but has 1/4 the runtime at the same light level.

I have found that a P7 (either flashlight or magicshine) is more light than I really need, except in very bad adverse conditions (heavy fog or rain), so the flashlight at medium power works great and gives me about 2 hours of runtime. I'll keep both now that I have them, but if I had to start over I'd just buy the flashlight (two actually - having had a light die on me on a pitch black road in the middle of a winter night, I believe you have to have backup)