Flyin'Dutch if I came across a bit strong, I apologise. I agree that in some circumstances you might need to bin the book and yes I forget the 1000' required height loss!
I was told by someone who had tried it that the early (Conti engined) 172's did indeed have a very marked nose drop in a steep sideslip.
You are spot on regarding sideslipping gliders, I have no experience of that at all. I have been known to prefer slipping Cubs and Austers into short grass fields though
