I have the Bernina 820 and it has a very large bobbin.
The Bernina 820 has a very large bobbin. You can fill it any percentage of thread that you want. There is a screen that tells you how full you are filling it and another screen that comes up when you get down to 20% and counts down until you are out of thread and it quits sewing. One of my other machines keeps sewing and sewing even when I run out of thread. Frustrating. I haven't looked at much about the 700 series, but I can tell you that i love the 820! It does everything but make dinner!!