We still have our 2015 Terrain before it goes back on lease end. The rear sliding seat is nice in both Envision and old Terrain as it frees up more cargo in the rear. The acoustic glass on the old was just the windshield and the front side window . Occasionally I could hear noise coming through the non-scoustic area behind my ear.
The Equinox doesn't get adaptive cruise control either. It is part of the Driver Confidence Package only the Envision Premium ll.
I think you can get a better deal on a 2016 Envision Premium l with AWD and 2.0T.
2016 Envision Prem ll