Agree, hasn't been out a year yet but am also looking forward to a compact version, hopefully a 3.6, 3.7, or 3.8" barrel length.. Good to see they're finally starting to add color options (in regards to the frame).
It appears SA has added colored grip frames for the Echelon. https://store.springfield-armory.com/echelon-grip-module/
FDE and OD (as well as black) are listed. Hopefully Gray will be added soon. As of now only the OD (green) Medium size with Standard texture is available
If you're referring to the slide rails in the frame I can see the front and rear are metal. The front locking block appears to have metal injection molding marks or casting. The rear is definitely MIM as the marks are very apparent.