Typically a print with an Epson aqueous pigment printer only last outdoors about 6 months.
In the same conditions a Roland print lasts about 3 years un laminated. But there is a possibility that white and metallic inks to fade faster, I don't know for sure.
Regarding the print quality: it is about the same as they both use the same heads. Maybe a little more flexibility for Roland as it prints via a RIP.
The answer is yes, you can print landscapes and I don't think the ink is less archival than aqueous ink, but you have to check the price: one liter of white and metallic is about 500 euros, way more expensive than Epson's inks.