From what I've read recently about ram jets, even though they can be fired up around 200mph, there's virtually no thrust. To get any sort of decent thrust it has to be going at Mach 3. Apart from that the prop/rotor wouldn't work very efficiently at supersonic speeds. Also the centrifugal forces the rotating prop/rotor would be under, I don't think there's materials nowadays that could be strong enough, let alone a country that didn't have any strategic materials they could get their hands on at the time (from what I've been reading about German jet engines of the time).
But then I'm like Jon, I just don't like all this Luft'46 stuff.