Wow this thread is exactly what I was looking for. I am in the market for a new set of fins since my SP twinjets (which I love) don't fit over my drysuit boots very well. One of my instructors offered to lend me his jet fins this weekend, he swars by them and uses them for everyting from tech diving to teaching OW classes. I will post up my report on the jets on Sunday.
One thing I do not like about the twinjets, is they love to float. Whether I am diving in a skin in coz or in a drysuit in SoCal, it happens and I don't like it very much. I heard the jets are more negative, so we will see.
Thanks Scubakevdm for posting your experiences.