I DID a search and did not find the answer to my question.  I know there are several buffers available/used in ARs. I see the Endine, MGI, 9m/m, H, H1, H2, H3, ad naseum.  I understand that the heavier the buffer, the slower the cyclic rate and their affect on felt recoil.  

Since I believe that the manufacturer knows which buffer is most appropriate for each version of their products, I intend to stick to the "stock" buffers in my ARs.  

So my two questions are, 1) what are the weights are for the different buffers and 2) is there a "good" reason to change the buffer?
Thanks