Are "compatible" pigment-based inkjet inks?

Background: A few inkjet printers use pigment-based inks, which for permanence around water and light are far superior to the mainstream dye-based ink.

There are also a few after-market cartridge manufacturers who claim to use pigment-based ink.

How do these Brand X inks compare with, say Epson DuraBrite®* ink?

I have searched the web and have not found a satisfactory head-to-head comparison, so I’m hoping someone at SDMB can answer this.

(*Aside - how do you make special symbols like the registered-trademark symbol in your posts?)