From what I've heard, the only problem with doing this is that the 1400 needs a profile to print correctly... you can no longer use it as a general purpose printer since you can't ICC out of Microsoft Office or your web browser. Plenty of people here have pigment inks in it. I bought the Workforce 1100 because it's pigment already, but I don't like the color gamut so I'm trying to sell it off. Tons of people here love it, though.
All the major ink aftermarket ink resellers stopped recommending pigment inks in Epson photo printers when they switched to the Artisan/Claria inks. I don't understand why, but it's probably just so they don't have to educate customers who don't understand ICC profiling. The R340 and lower series worked without a profile.
Pigment ink is more likely to clog than dye but aftermarket ink is less likely to clog than the fast-dry Durabrite Ultra inks. I suspect most complaints are from people who go all out and buy a pigment CISS, etc, then only print once a week or less.