A year or two back, I was curious to see the effect of flying too slow in a sideslip so I tried it in the Skylark. She certainly did not do anything dramatic (she's a real Lady, mind), there was no 'flick into a spin' or anything like that. As I remember, it was just like approaching the stall but with more buffet and general airframe shaking. I think she tended to run out of control to the point where it was difficult to keep the slip on.
I suggest you all go out and try it, at a suitable height, of course.
I don't know if it has been mentioned earlier but sideslips don't work all that well if the speed is too high. Normal approach speed is about it. Any higher and you just won't get the sideways attitude.
Mike W