While this is mostly true, I think that enfuse has the advantage of exposing many more parameters that you could tweak compared to the typical tone map operator, including ways to deal with noise. Take this tutorial for instance, Retinex has regularization but not Mantiuk 2006. Another implementation might have it but that is still one control.
You mean gains in noise reduction. 
In this case, I would include the outputs of the raws (TIFs) in addition to the HDRMerge DNG for enfuse to process. That way, enfuse is able to catch what HDRMerge missed. After all, HDRMerge is just one algorithm with its own limitations.
Anyway, as I cautioned @gadolf before, I might not know what I am talking about 
. You would have to test what I have said and correct me if need be. 