My friend gave me her Bernina 820 and bought the 770 and loves it. The 820 also has thread cut and I love it, unfortunately for me the Bernina needs to go to the shop. I'm very happy with the threader, some machines I hear get out of kilter. Even my bottom of the line cheapo Brother's threading assist is better than anything my vintage machines have.
I've seen reports of other machines and complaints about how much thread the auto cutters leave, not the Bernina! I have no need to go back and track down threads at the end of the project.
My current project is a Lemoyne Star and I'm setting in the corners and the triangles using my portable class machine, I am missing that thread cutter so much right now...
I also like the knee peddle for foot up/down, my friend who gave me the machine never used that. With the 820 you can also use the foot pedal to stop with needle up or down, I like that too. The Bernina has buttons that can be used too but they are hard for me to read while it is easy for me to tap my foot or swing my knee!