Thank you @obe, it is a very nice photo.
Actually, you had a specific query about using Retinex on this particular image. Thus, for the first half an hour I did try to use that tool to get a result that is satisfying to me. But I failed. Then, I started all over again from the Neutral profile and spent another half an hour or so to finally get something that I was happy with. Then I debated for some time whether to upload it or not because it strictly speaking did not answer your question. Therefore, I am happy that in the end, you liked the result of my efforts 
Now, to answer your question about uniqueness of Retinex, I feel ( due to my experience with RT over a period of time) that the correct approach to use RT is not about using a particular tool but to have an idea of what one wants to be the final image and getting there one way or another. RT is not a collection of tools that operate on disjoint circumstances. Rather, it is an amalgamation of (almost) all possible tools that can be applied in a non-destructive way to a RAW image. Thus, many other tools may combine to make some particular tool completely redundant. RT is not bothered about it. I really like this approach because, it gives you a choice to reinvent yourself in a familiar setting of a known programme (rather than having to know a new set up to get hold of new tools).
In short, it is my understanding that the inclusion of the Retinex tool in RT need not necessarily imply that there exists a circumstance that can be tackled ONLY by it. Of course, there are more knowledgeable people here and will like to know what they say on this. Cheers.