Although I personally haven't, I know people who have b/c they thought they wanted embroidery and found that they just didn't use it. Same for the stitch regulating machines (sorry, while I know Bernina's are called BSR for Bernina Stitch Regulator, I don't remember what Pfaff or other manufacturer's call theirs).
I won't deny that when I see those shiny new machines, or a friend gets one, that I don't think for a minute or two that I want one. Then I remember that I have two Berninas - one bought as my splurge for myself after my dad passed and left a bit of money, the other bought used as it is a smaller machine for travel, classes, sew-ins - that I love as much as the day I got them. They sew beautifully and finding a new one that sews as well but does not have bells and whistles I don't want would be difficult anyhow.