UltraMax K3 inks?

Can someone share experience using those inks? I am tempted to switch from the original Epson Ultrachrome K3 on the Epson 4800 to the Ultramax inks, available at a fraction of the cost. They advertise a wider gamut that brings more vivid colors. What is not clear to me yet is whether the inks will produce natural colors suitable to landscape photography, and if usable with the original Epson driver and custom paper profiles, or if a specific RIP is needed. Best regards Paul Schilliger