Well, I'm slightly confused about this http://brian-mountainman.blogspot.ca/2010/11/sacred-stones-and-madagascar.html blog and response, but I will give a  go at a response of my own.
In his blog post, Brian John critiques the analogy and thoughts of a Malagasy Anthropologist Ramilisonina. Now, again, correct me if I'm wrong, but the issue brought up by Brian John is the analogy created by Ramilisonina between prehistoric stone and wood formations found in Southern England (Bluestonehenge, and Woodhenge) and rock monuments created for the deceased in Madagascar. I believe that John has an issue with the assumptions and the forced parallels that he feels Ramilisonina has made. In my opinion, I would have to err on the side of caution, and agree that it is far fetched to make analogies as Ramilisonina has done. However, it is only an analogy, and he is not stating that there is deep-rooted relationship between the ritualistic practices of the two areas. He has not suggested that the two areas must have come in contact at some point, with one taking a practice from one or the others. The "Father of Anthropology"Claude Levi Strauss looked at the cross-cultural similarities that show up throughout various cultures, who realistically had never come into contact either physically or through diffusion. In archaeology people are forced sometimes to make suggestions and inferences in order to make logical conclusions which can be backed by scientific evidence. The problem, as we all should know is that a lot of archaeology can only be inferred upon to a certain extent due to the lack of historical information on those people. Sometimes all we can do is pull ideas from other peoples habits and cultures in order to try and make sense of things we may not necessarily understand. In the case of Stonehenge, we don't know for sure why such elaborate structures were made, it could basically be for any of an infinite amount of reasons, although some may be more logical than others-- but again, we can't assume that they are 100% correct.
I think it is illogical to create an analogy between the two sites being dealt with here, but again, I can understand why it has been done. Archaeology thrives of theories that need to either be disproved or proved, which means that until something is definitively proved, it may be easy to find 'evidence' to back a theory. I recognize that this is a little bit of a tangent in a different direction from the original analogy question being asked here, but I figured it may be fun to play devils advocate for a moment as everyone seemed to have picked the same side on these blogs. I think it's logical that since Ramilisonina and MPP have been working in these two areas which have a similar undertone to them, it could eventually lead to them having an opinion that there are certain similarities across these cultures.
One more thing, something that really got to me in the interview was the definitive language used; for example: Stonehenge "was a sacred place where people came to make contact with the creator gods and the spirits of their ancestors." As far as I've heard, that hasn't been concluded. It states that that is 'in his opinion' but still, something that people should be cautious and conscious of.    
Right, okay, this ended up making less sense than I wanted to. Apologies, apologies.