Re: To sutemi, or not to sutemi
We use sutemi techniques and study them. I would never describe them as inefficient, the throw s are very strong and directed with a lot of intensity. If I were to look for a weakness in those techniques it is the narrow safety margin while learning, since gravity operates on both Tor & Uke and can't be slowed down.
My teacher teaches the proper opportunities for sutemi techniques are normally when Tori is already on his way down, and wishes to take Uke with him. Kind of "don't go down alone" mentality, obviously, this mentality may also be constructive in multiple attackers situation, though rarely.
Obviously, we practice sutemi techniques in randori as well, and they are sometimes used as Kaishi waza (counter), between the more veteran students.