Yup, you pay for the gamut. In general better media costs more. You also pay for the problems associated with the much thicker substrate, the best one of which is head strikes on the curled up edges which develop one edges of thick canvas that are off the roll for more than a few minutes. Nothing is free. Fortunately, there are ways of dealing with the curl, the chief one of which is to concentrate lots of printing in single sessions. On my 8300 it also helps to have supplemental push-down clips riding each edge. And at least for the Epson gloss canvas, recent batches have used a much softer substrate that almost eliminates the problem.
The gloss canvases can give you prints that are much stronger and much more dramatic than with matte canvas. You can pretty much duplicate the look of good photographic papers, if that's your cup of tea. Aesthetically speaking, the majority of art buyers respond favorably to eye-filling color, and only the minority to something like subtlety. There is a direct, non-inverse relationship between amount of color, competitiveness, and profit. And while such statements will surely be used against me when the Art Trials come, I must nevertheless stand fearlessly by them.