Ok, so this is the "modern" 820 Sewing Computer, it has a huge throat space and it is the model that did not go over well:
https://www.bernina.com/en-US/Machin...0-QE#!overview
The vintage ones had a much shorter throat. Those are considered to be pretty sturdy little workhorse machines, but I don't have any knowledge about them.
I have a modern 820 that was given to me by a friend who is a Bernina fan. She bought it from another Bernina fan. Both were not a fan of this machine, but I like it fine. Both of the previous owners have gone on to the 770 to much joy and delight and are still Bernina fans.
I was told it was fussy with threads, and after about a year of use I had to replace a thread sensor. But I just use quilting threads and my friend likes to use fancy threads so that may be a different issue. Some of the 820/830s do seem to be lemons, I don't think mine is. I've grown to love many things about it. We have a couple other people on the boards who also own the modern one, and we have quite a few with the older one.