Hi,

All three Velvia varieties will behave differently. 50 is very saturated and has very warm warm hues. 100 is very saturated, but the warm hues are cooler. 100F is highly saturated, but not nearly as much as the other two kinds. It is also less contrasty IME.

The 100F is the most "normal" of the three IME. I use it more than any of the others. I particularly like it for still life pix and twilight landscapes.

I would put in the effort and expense for an initial test of the range of these films, and push and pull tests. It is a P.I.T.A., but it gives you so much information about the films that you can use in the future.

I would start with a plain old bracketed towel (or any textured fabric) test, and see where your film drops off into black on the low end, and into clear (white) on the high end. That will give you a rough idea of the film's ability to hold texture on either side of middle gray.