Oh, re Crag Martins' comfort level in flight, here they nest up on some big cliffs around 10 minutes' walk away.
It's a nice spot: Wallcreepers in late winter/early Spring, Alpine Chamois, and due to the uplift, not a bad place to spot raptors (Golden Eagles, a passing male Hen Harrier, buzzards (Honey and Eurasian), kites (Black, and Red), and Goshawk). Peregrines nest there too, along with Ravens, but were absent this year for some reason. In autumn, the Nutcrackers are very active, and the Black Woodpecker, like the Jays, are easier to see.
The Crag Martins seem to rub along quite well with most of the birds, but I have watched them pulling the tail feathers of loitering Sprawks...