Re: shiho nage
Shiho Nage is my favourite technique. Mainly because I'm only 1m70 tall and light on my feet.
One thing I've been thinking about though: why do most people even high ranking teachers, execute it so badly? I see a lot of people lifting Uke's arm above uke's shoulder line, or even above or behind tori's head. That will work on 99% of all aikidoka because most of us are "programmed" to react in the "correct" way (read: they're being overly compliant). On beginners, though, it suddenly doesn't work anymore: they keep making cute pirouettes because it's the natural way to react if you don't know anything about aikido.
I've spent some time looking into that and noticed that a lot of people tend to loosen the initial extention and thus restabilize uke, allowing uke to pretty easily drag tori to the ground. Another thing is that people can easily do pirouettes if you lift Uke's arm above their shoulders. Keep their arm on that level or slightly below it, while keeping the extention, and you're set. These two mistakes are very closely related, and one often leads to another.
This does make Shiho Nage a bit more dangerous than most of us would like, though, especially with a slower/older/stiffer uke..
I find that shiho nage is a lot like ikkyo in the way that it looks super easy but is pretty hard if you want apply it correctly.