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 :)
On the P1S its a couple of connectors and two Allen screws (assuming you have a fully assembled hot end to swap in). On the X1C its the same but three connectors. The new P2S is coming with a quick swap nozzle feature which would definitely be worth it if you plan on buying one of their printers.