Interesting comment in that link given by Bookworm.
In over 2500 hrs flying Cessna 170's, both the small flapped 'A' model, and the Fowler flapped 'B' model, and always using full flap forward slips to get into fields and farm roads - never a sign of instability in pitch or any tendency to snap. So, I'm unsure about their advice.
Have also used a slipped approach for many hours of farm and bush flying in Cessna 180's and 185's, Cessna 182's, and SuperCubs - and no particular problems.
Have found that it's best to cease the slip above the treetops, or anywhere that windshear might be lurking, so that there's some spare height and speed to allow for a roundout.
happy days,