I seem to remember that time when I thought, "damn, this plane is a dog in climb", only to realize that the friction nut had come loose on the power and the rpm had dropped to somewhere around 2000 rpm. This was in a fully loaded 172 and she still gave about 300 fpm.
Next time I'm up I'll experiment with this and see what rpm I can get. But I think that 1900 rpm sounds a bit high, but I could be terribly wrong.