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 :)
Love me some quick swaps, I'll probably be checking one out eventually. I like Prusa's mozzle design, but they're flippin expensive for hardened, and torquing the adapter to a standard mozzle has been a certified PITA