A feathered prop is also much quieter than an unfeathered one on a prolonged taxi. Also in the Saab you will see your prop gearbox oil temps spike in the unfeathered position if you are sitting still on the ground on a warm day. Feathering allows oil back to the reservoir which = cooler oil.
As previously mentioned, CJC's procedure to help keep the cabin cool is to run the high pressure bleed valves with one engine feathered and the compressor spooled up a bit. This is why so often you see the Saabs taxiing with one engine unfeathered and one feathered. We are in there sweating like a cub scout at neverland ranch.
