On the topic of cross-over material, I would also like to see feats that offer Stamina system support. For example a feat that allows you to regain or switch Martial Focus as a Move action by spending X stamina points, as a Swift action by spending 2X stamina points, or as an immediate action by spending 3X stamina points.
I would prefer that such Stamina integration is done via feats, so that people using Spheres of Might dont need another book (Pathfinder Unchained) to use basic talents; but are still available to those that do use the Stamina system.