The simpler Bernina are outstanding machines, but most people I know with a 820 or 830 seem to think them temperamental. I have a 440 that I wouldn't trade for the world for general sewing. I do a lot of piecing on my vintage machines (Singer 99 and 221 mostly). I finally bought a Sweet 16 sit down mid arm for quilting. It seems like the best characteristics for piecing (narrow feed dogs, perfect straight stitch) just don't fit with the decorativnet asks the computerized machines are designed to do.
Hope your dealer lets you trade down.
Pam