Just from my own experience, I print my stuff on a high-end color printer that uses the Splash rip system (Its a 35 grand printer, and I get to use it at night when the place is closed). I figure on the basis of 100 dpi, and Ive never been disappointed with the print quality, even on high-gloss paper. Anything more than 250dpi is pushing things into the silly region, to be frank; even high end art magazines rarely go over 300dpi.