I think both surfaces have their place. I love matte fiber B+W prints, and the matte surface has its own character to it. However, the real reason to do RA4 printing is that the gloss prints you get from that have a more natural gloss than inkjet papers. For that the gloss is very nice. It's like you're holding a slab of awesomeness in your hand.

Have you tried some sort of laminate? That will give you a very nice gloss. I don't think it would alter any tones though.