Originally Posted by
dougmc
Well, except for the old or new battery pack. (I'll assume you don't remove the light head to change the battery, which is probably a reasonable assumption.)
Unless you have both battery packs mounted simultaneously, in which case the appropriate comparison is somebody with two flashlights mounted simultaneously and therefore also has nothing to drop when switching lights.
If you're looking for advantages of one over the other, "fewer parts to drop" is a pretty minor one. (Unless it's a race and you can't afford to stop while you swap lights. Might be more important then.)
I said you could drop the external battery pack above. It's not likely to get lost when you drop it. The same can't be said of the parts from a flashlight.
And, if I'm going to carry around two lights (or 10) on my handlebars, I'm going to have
all of them turned on. No sense carrying them around if you don't use them. If I carry two lamps with external battery packs, I'm also going to be using both of them. I may not use spare battery packs but, if necessary, I can rig those spares in parallel to extent my run time, as I've pointed out previously.