I am sorry for all the people having problems, but my Prusa mjni is finally just workjng and happily printing all the stuff I throw at it. Its been having issues here and there forever. I just figured out that the hotend has not been assembled correctly (heatbreaker to nozzle seal was weak) which became a greater issue when switching to a 0.25mm nozzle. Now after I fixed it, it is just awesome :)
It’s getting closer and closer. A good modern printer is largely fire-and-forget. Still takes some know-how, but far less than it used to.