Interesting exception Tinstaafl. The DA42 with Thielert engines has start latches designed to lock the propeller just a few degrees away from full fine. If an engine malfunction occurred in flight with the blades in the intermediate pitch range (that is, already "beyond" the start latch position), they could feather from any RPM at all.
This happened to me when the propeller control valve failed, so blades oscillated between full coarse and fine, with associated RPM oscillation. At low RPM the blades were at full coarse with start latches unable to engage.