I hear what you say, but just because RAW's capacity to store dynamic range is similar to what the human eye can see, doesn't mean that it can retain the desired richness in detail in both the highlights and the shadows when the capture device is faced with a scene where the range goes to extremes. You need to remember that we survey a scene differently when we are present at the scene, than we do through a 2-dimensional photographic representation of that scene. In real life, we make adjustments with our irus depending on which way our head is turned. Other adjustments are also made on a chemical level (cones and rods) as well as psycho-visually in our brain.
A huge function of the 2D photographic representation is the interpretation to convey the interpreters ideas of the original scene. To this end, they may take an any means necessary approach to secure their very own (and subjective) interpretation.
Specifically in this case, I may choose to forgo some image replication integrity subtracted by a filter, in order to arraign details in the shadows along my camera and it's RAW format to wholly accommodate not only the shadow detail more comfortably, but also now the highlight detail due to the fact that it has been compressed before it enters my recorder. Furthermore, I have changed the profile/distribution of the detail - depending on how that particular low-contrast filter functions.
You must remember that the outcome of this change will take on different signifigance in different situations. I don't accept that one can intellectually theorize that there
can't be a signifigant improvement in the quality of shadow detail redistributing the spread of the shadow detail through a filter. A lot will depend on the successful design of the filter, but there are so many factors, that the only viable way to get good information about how much it will help, is to try it out. Hence, asking for experiences of other people who may already have tried it out.
I don't have much money to experiment with, so I am going for the Lee system. The annoying thing is that I can't get my hands on the lee low-contrast filter until July. There are a lot of people using the low contrast filters for various reasons in film. I like the idea of not having to spend too much time munjing and image in post in order to do something that can be achieved through the trivial act of mounting a filter on to the lens.
Many experienced digital darkroom practitioner-photographers will vouch for the fact that it is too difficult to achieve the same quality effect in post, than it is starting with the filter.
I will still subject my work to post, but starting off with a data set which more resembles my desired interpretation means less munging in post - and less work. Munging in post is destroying data. I do it all the time, but the only improvement in detail is simulated. Besides, when you have a different starting point, you end point is likely to be different in this case.
Put simply, if you have a scene where the highlights aren't so high, and the shadows aren't so low, there would not be any point in using a contrast reducer. But if the shadow detail is really far apart from the desired highlight detail, then a low-contrast filter drags them within range of the RAW file - which is not infinite. The range of the human eye at any given iris size is also not infinite - so it is not useful as a benchmark for what needs to be recorded by the camera.
To use an example, if I could take a photo like
the one here of a scene at sunset taken with a telephoto lens, and through some amazing new technology, I could get all the details in the shadow (which are currently silhouetted) and the detail of the surface of the sun - solar flares et al, then that, to me, would be way cool. It doesn't matter that the human eye is not capable of seeing that in real life, what matters is that I now have that detail at my disposal for generating my 2D representation via the post-production process - bringing everything (or at least what I chose) into the range of my output device. That's what matters, and that is the purpose of dynamic range compression pre-capture time in order to fit it into a recording device/format that is necessarily limited in dynamic range.