i've used my SP540 on photo paper, quite a bit actually. i like it. prints out fairly impressive. i've got a few hanging on my livingroom wall that i printed out actually... framed, etc. and some more in the bedroom of my cars that i've taken. my point is, the quality is good enough for showing off. infact, we print posters for a local business for advertising at their stores. doing up 12 more posters later this week. they frame them, and hang them in the entry way.
i personally did not like the Roland Photopaper samples that came with my printer... I DID like the Neschan brand that came as samples, so i ordered another roll of it (54"x164'), Satin Photo Paper, Part # NES6025065, price was fair for what it is. i think they also sell a half roll as well.