Posted By William Chang
Although I haven't used an Apogee RA88, based on the concept and people's reviews, that's the one I would recommend. It's quite heavy, but mounts like an alt-az telescope.
The SkyWindow concept has potential issues such as mirror flatness (they do sell a more premium version, which raises the question of how premium), dust on the front-surface hard-to-clean mirror, and the fact that you have to do mental geometry to figure out where in the sky you are pointing! (Remember that the image is upside-down and the angle of reflection is not constant, IIRC.)
If my skies were darker, I think I would invest in a nice large pair of binocs. But like I said, 35-40X makes a huge difference in darkening the sky background.
Another thing in the RA88's favor is the possibility of using light-pollution filters.
p.s. And as you know, I'm building a Borg 100 Achro binoscope :-)