[sterlind]

I think it wouldn't be slowed, blocked or dissipated by matter, other than interference with other gravitational waves or time dilation from passing through curved space. I'm not sure what benefit it'd have over neutrinos, though, since those share those properties.

[amelius]

Imagine a 100x100m neutrino detector, and how difficult it would be to hit that surface with a neutrino over a distance more than a light-year. Or conversely how strong your neutrino source must be if you radiated in all directions.

[pmontra]

Easier to detect?