In retrospect I see your point... I've used the slip a fair amount of times in a tailwheel - but usually it's just limited to tailwheel...have never really needed it other than crosswind. The "mushing" is like usmc-sgt said a back country technique for short strips. You can come in stabilized at a slower speed than say a slip... but it's all different strokes for different folks, whatever floats your boat....

The danger I see in a slip for a primary guy is getting a really high descent going, and then instead of releasing pressure, just pulling back on the yoke/stick to arrest the descent and ...

In the Caribbean, the 'mushing' (can we call it something else?) technique seems to work coming over the ridges and mountains to a small runway. The aircraft really isn't that close to a stall, even if you did start to buffet you can just drop the nose a little and/or add a bit of power.

Now, I wouldn't use this technique in a twin.