These diodes are very efficient and I see similar output to DTR's ie 1.3W/A.
You will see the spill. A bad or improperly rotated wave plate absorbs nothing, but causes the light to fail to pass (or be properly deflected) in the PBS. If this is occurring then the wasted light will either exit the PBS toward the other diode or as in my set ups, will strike the surface that is glued to the adjustment mount. This might be missed, I suppose, if the mount is black anodized, but you should still be able to see it.
I am still worried about the diode. I run my 9mm diodes at 2.3 A and get 3W out of them.