Hub4 is IEEE802.3at, so any injector that supports it... However the dp48 uses ieee802.3af according to my notes, but I assume that at is backwards compatible with af...?
I think it varies from manufacturer, but I do know that there are many af (PoE) devices that will work with the at (PoE+) standard. It seems like it really boils down to if the PoE device actually adheres to that standard and is not something proprietary (ubiquiti, etc), then it should be able to properly initiate a connection with a PoE+ source.