I tested Bay Photo's aluminum prints a while back. Very good fade resistance, but not as goods as best inkjets. In 6 months of sun they faded noticeably in the sky. Inkjets had little fade after 1 year of sun. Still, metal prints are pretty archival and showed little overall fade with 6 months of sun. The 1 year sun test was for gloss optimizer. It seemed very archival. No yellowing or difference from 1 year sun exposure. (But time will tell.)
The beauty of inkjet is you can display a copy and if it fades, just print up another one. Dye transfer prints very quick in strong light. Never display the original.