im looking at my test prints with these papers from my epson 3800. the only difference i can tell is the photo rag is warmer and has a smoother surface than the fine art.
That is what I see too and what I have measured. The HM Photo Rag Baryta 315 gsm Lab 97.8 -0.2 2.2 is warmer and slightly smoother than the HM FineArt Baryta 325 gsm Lab 97.4 1.4 -3.9. The last is an alpha cellulose paper which is something I have no problems with.
When I put next to the two samples the HM Baryta FB 350 gsm Lab 93.7 4.1 -8.9 (the one not asked about) I see a much more cool magenta/purple paper, slightly more gloss and the two other samples show much less difference to one another than to this paper. The main thing is that this paper does not reflect much green, its whiteness depends on OBA content (blue emission) and the fiber white at the red end. In absence of UV light is will be a dull paper. Without testing it is hard to say what the lifetime of the OBAs is but the dependence on OBAs and the lack of other whitening agents makes it a risky choice. I do not object to its alpha cellulose base.
Met vriendelijke groet, Ernst
340+ paper white spectral plots:http://www.pigment-print.com/spectralplots/spectrumviz_1.htm
update april 2012: Harman by Hahnemühle, Innova IFA45 and more