I can't speak for the Bernina's, but dearly love my Janome 10000, upgrade to a 10001. Have never had a problem with it and it has a stitch speed on it (not called a stitch regulator) and would suspect that the newer modules probably have a stitch regulator by now. Would love to have their newest model, but can't justify the price for the sewing I do. The instructions with the Janome are very plain and easy to understand and the machine itself if very easy to use.
As several have said the dealer has a lot to do with whatever you get. No good dealer, and if you have problems you are up a creek without a paddle. While I have not had any problems, I don't think there is a machine built that some of them don't have problems at one time or another. Some just have more problems than others and you want to stay clear of those. Good luck in whatever you decide.