Anyone care to extol the virtues of these three beam combing methods?

Seems to me that brewster plate beam combining is very close to knife edging and a lot easier to align. I assume this is a flat piece of glass that totally reflects the beam at the Brewster angle while the other beam passes through the glass unchanged. The glass would be coated as well I assume and you would have to come at the plate at a weird angle. If this works that way you should be able to stack a lot of beams this way with minimal loss. I think I figured out why not ....same as pbs. Polarization. Never the less neat method.