I think Baldeagl is right and Krusty is wrong.
Ditches DO NOT count against your K/D. I have no idea with respect to kill multiplier.
If a guy ditches a certain distance from you, you get the kill, if far from you, you don't get the kill. What is that distance?
Is it that a ditch in friendly territory=no kill, ditch in enemy territory=kill? ie. if you get a successful ditch there is no kill awarded, if you get a 'captured' then someone gets the kill? I think this is the case.
I banged an enemy plane HARD one night, he was definately going down, and I never got the kill or assist. I'm positive he didn't RTB. We were right near his town. I think that was a ditch that didn't award me the kill.
Finally, despite the detour, no worries on waiting on the kill. I've done it too, but only when I had some other compelling reason to hang around (ie. beer run, pee break, etc).