Hi Jim /ubbthreads/images/graemlins/wink2.gif
Well your post limits us to the:
6p
G2
G2z
Z2
M2
C2
(I think /ubbthreads/images/graemlins/smile.gif someone please correct me if necessary /ubbthreads/images/graemlins/grinser2.gif /ubbthreads/images/graemlins/twakfl.gif )
I've seen the Z2, M2, 6P and the G2z. Of these, I own the G2z. Not surprisingly, my pick is the G2z /ubbthreads/images/graemlins/rolleyes.gif /ubbthreads/images/graemlins/smile.gif
I will find the thread(s) in which I, and others talked about our choices and reasoning (I could answer again but I think that thread was very comprehensive and worth reading). From memory I think it might give you a good review of information on at least some of the above Surefire 2x123 P60/61 flashlights.
If you haven't found it yet, I recommend using the search function on cpf, it will give you a lot of information in addition to the replies you receive in this thread.
Is this question just for general interest, or are you trying to figure out which one to get /ubbthreads/images/graemlins/naughty.gif /ubbthreads/images/graemlins/hahaha.gif? Do you have a particular purpose in mind, or is it just for general use?