Hey jbrett14:
Yes, the Streamlight is excellent quality, but the Arc is better, both in the quality of components, its engineering and its design. Even little things like the pocket clip is better (thicker, stronger and better anchored) on the Arc. The SL uses a non-clickie switch, while the Arc's is state of the art.
I like the SL and I do appreciate its quality, but it can't match the Arc. Then again, Arc seems to be having quality-control problems and I would never buy an Arc 2nd -- just too much of a gamble for the money.
But the real test for me is which one I use: I never use the SL. For general use, I alway grab the Arc 4+. If I need more brightness, I grab the Surefire L6. If I need more than that, I grab the TigerLight.
Josey