I am now in the final stages of assembling my bp/wing set-up. It would have been sooner, but the LDS accidentally ordered an aluminum bp when I wanted a steel one. There are several staff members at my LDS who have bp/wings, and they have been very generous in allowing me to use theirs when they were not using it themselves. I definitely like to use bp & wings, which is why I went about getting one for myself.
When I am not so lucky as to be able to borrow a bp from someone else, I use the jacket style bcd's that the shop rents. I don't mind using it, and will probably continue to wear it when in the pool with students. The jacket style bc's are easy to deal with, and meet my needs for most of my diving (which, these days, is mostly with students anyway.) I have also used a back-inflate style bcd without a backplate, but I didn't like it that much. However, if I was going to buy a non-backplate bcd, I probably would get the back-inflate type rather than the jacket style.
Once my steel bp arrives, I will probably always wear it in open water, with or without students.