There are two main types of lighted nocks, Lum-i-nocs and tracer nocks. Hotburn76 you were right in that some people claimed that one brand did not stand up, broke down and failed on a regular basis.

I should probually not say the name, because I am not sure if I am remembering correctly, but I believe that the Lum-i-noc brand was the weaker brand.

I will be getting some at one point because mostly I love to see my arrow in flight towards the target. I want to see if there was any unseen twigs, wire deflect my arrow. Plus if shooting into a large black target (Moose, Bear) your arrow will disappear in flight unless you have very bright wrap or fletching (not for me as I use my arrows for turkey, need dull arrows).

They do have their place and if they save you one arrow, they more then pay for themself.