I have read everything I could find on the dry mount v. corner mount debate and have found that there are good arguments relating to "archival qualities" of both approaches. To me, it boils down to personal preference and your working methods.
I quit dry mounting prints about a year ago and moved to corner mounts behind window matts. The reasons: 1. Over the years I have ruined several dry mounted prints by dropping the mounted prints on their edge. The edge of the matt got banged up and looked terrible. A new window matt hides the flaw in a frame, but I could never sell the photo or show it out of a frame. I had to reprint the photographs and re-mount.
2. The matts tend to get dirty over time when they are handled. I like to replace the matts every so often, particularly for workshop prints or prints I show loose.
With corner mounting, if I mess up or the matt gets soiled, I just removed the photo from the matt and mount on new boards