I recently got a Surefire M600C in a trade the other day. I like it, but I dont see myself ever using it. Is this a light to keep or should I just keep it for sale on the EE?
I love M600c’s. Lights much like optics are all about personal preference. If you put it on EE, I maybe interested.
That obsolete piece of junk?! I’d sell it. I’ll take it off your hands for $50, but only because I’m interested in older lights. j/k 
If you don’t care for it, you could always sell it for an x300 or whatever floats your boat and you’d still have some cash left over for some ammo or what not. 
Not sure why it has recently been en vogue to question the efficacy of the Scout light, but for my money, the M600c is still easily a best-in-class lighting solution.
AC
Its cheaper to buy a X300 for use on a rifle instead of the Scoutlight family of weapon lights.
However, when you run a low light class, drills, use in real life (LE/MIL/Home Defense) you see the advantage of the Scoutlight with a SR-07 dual function tape switch.
I have two X300’s and two 600A’s. Both 600A’s were bought used and cost me the same as what one X300 was new. I just don’t see why the 600’s are suddenly “out of style” either. It’s silly if you ask me. Keep it and use it. If not, I’ll give ya $120 for it! One can never have too many lights! 
+1 on what AC said. Hold onto 600Cs like good whiskey.
These are great great lights. I would keep it, I regret getting rid of my scoutlight.
I’ll buy it, lemme know.
I have a Surefire-M951 and think it is the best. Surefire makes great lights. If you need or want a light to mount on a rifle I would keep it otherwise sell it.
I agree, I use one on my guns and find it to be an outstanding weapon light.