Edit to my previous post: looking at my Ergo Pro, the padding on one of the wrist rests is permanently squished in one spot after 1 year of moderate use (alternating with another keyboard). It still feels fine, but the difference is visible. My guess is that tenting rotates the arm so that its weight is concentrated at one bone on the outside of the wrist, and Matthis didn't take that into account in choosing their padding. Heavy users might need a new wrist rest after 1-2 years.
Unrelated: the extra Ctrl key for the right index finger comes in handy.