Many thanks for the thoughtful advice.
If I wasn't outsourcing the printing and framing to a local shop I would certainly make two prints and see whether glossy or matte looked best behind glass. I don't own the 3800 - I have the Epson 2200 and used to make matte prints on Moab Entrada with a custome profile through ImagePrint, but I didn't like the 2200's output with highly saturated images. The combination of deep blacks and high saturation in this photo made me think the Baryta papers and Epson 3800 or 4880 would be best.
It turns out that the place where I'm going to have the print made only offers the choice between "Hahnemuhle Photo Rag, Moab Photo Rag, Textured Paper by Crane, and Exhibition Fine Art Fiber" so I will probably go with the Epson Exhibition Fine Art Fiber. I would have preferred the Ilford Gold Fiber Silk for its reputed warmth, but I understand the Epson is very good in terms of dmax and saturation, even if the paper is somewhat cooler. The only trouble I foresee is finding a matt that is a good match for the colour of the Epson Exhibition Fiber; I plan on matting the print with a bit of a gap to show the paper-white around the photo. (Any recommendations on matte colours that look nice with EEFAF would be very much appreciated).
As I will be matting the print, it probably won't ever touch the glass. I was worried reflections off the surface of the print might be exaggerated by the effect of having a reflective piece of glass a few inches in front, but it sounds like this will not be an issue if the photo is properly lit.
Regarding reflections and museum glass, is museum glass the same as anti-reflective glass? I once had a few art pieces framed under the anti-reflective glass, and I must say I don't particularly like the hazy look this type of glass produces, especially in situations where there is considerable distance between the image and the glass.
Perhaps I will follow the suggestion to print the image on Epson Exhibition Fiber and then frame it without glass.
Thanks again,
Fabrice