It is pigment ink, but the OEM ink tends to shift color balance when heat pressed. You can either attempt to compensate for that by tweaking your image and/or print settings, or use a third party pigment ink (like Cobra) that is made for heat pressing.
I think the only really difference between those printers is the price, and that the 7210 is just a printer: no photocopying, etc. I went with the 7210 and Cobra ink in refillable carts. Cobra provides color profiles for use with transfer papers and such.