Another negative with using the surefire...you'll be burning through lamps really quick if you use the standard p60 lamp, and at $20 a bulb that's gonna add up to the cost of a Fenix quickly. You could buy the p60L lamp assembly for $39 to upgrade your surefire to an 85 lumen led light, but if you're gonna spend that much you might as well buy a 200 lumen Fenix for $60. The fact that you already have a 6P implies you're willing to spend good money for a flashlight (it currently sells for $59 on the Surefire webpage) unless somebody gave it to you or you acquired it free/cheap some other way. The slippery slope of flashaholism strikes again!

I remember reading about at least one user here who uses a number of 3W LED flashlights from Dealextreme. They put out less light, but cost less than the Fenix lights. With the lower cost I've heard there are sometimes problems with quality control and such. Shipping also takes a long time since the items ship directly from China. I think I'd rather just spend a little more at Fenix-Store and know I'm going to get a quality light with fast shipping.

But after re-reading your post, it seems like you're going to be doing most of your riding during the day, and maybe you are just looking for a "just in case I'm out too long and it gets dark before I get home" light. In that case the Surefire would be great, since it's lightweight and runs off lithium primaries which have a long shelf life. If you're looking at using it maybe 10 minutes at a time as a "got stuck out in the dark" light the Surefire could work. If you're a commuter or specifically plan on riding at night, spending a little more up front will save money in the long run.