i am interested in finding any experiments (proposed, underway or complete) that test the cosmic version of the delayed choice experiment. i am not considering that the experiment will fail, but rather am interested in if there is any distance (and subsequent time) factor that needs to be considered.

with the sum over histories approach and the terrestrial delayed choice experiment, is it that the photon is still taking all paths ie maintains is wavelike property but the in-line second detector skews the probability enormously towards detecting a particle or does the second in-line detector eliminate the probability of any wavelike property being detected ? in other words is it still probable that you will catch the photon out and see it taking all paths or has this path been completely eliminated by the second detector ? if it is still probable, then how is the "very small" probability worked out ?

are there any delayed choice experiments where:

a - the photon has been slowed down ? or is it that the experiment only works with photons traveling at c ?

b - a "particle" that has rest mass has been used ?