I heard the Treehaus speaker with the rebuilt fieldcoil driver. It sounded okay, and looked fantastic, but I have heard other speakers with field coil drivers in similar applications that sounded better to me.
Both the V1 and V2 Songers sounded better to me, for example, and are competitively priced. There are some very expensive field coil systems, such as ones made by Voxativ that sound terrific. My favorite system employed an ancient Jensen M10 driver and a tweeter in an open baffle bass loading scheme.