I bought the Sapphire 830 when it first came out. No problems with it at all. Have had it serviced once just because I thought I should. It is a great machine, just wish I had bought the 850 for the embroidery but could not afford it.
I love the large throat area and the needle down with pop up foot. Wish it had a stitch regulator is all.
Bernina is just to expensive.
I have not had to adjust the thread tension when free motion quilting.
By the way, how much do they want for it? I paid 1100 for mine when it was new.