You can use Inspira needles on any machine. They will not hurt your Janome at all. That is pretty silly since your dealer tells you that simply to have you purchase 'Janome' needles. Janome does not make needles. Inspira are made in Brazil and are of very high quality. Iin strength, they are more along the lines of industrial needles. You don't have to change them as often since they are stronger and the eye is slightly larger to help accommodate thicker threads without shredding or looping. I know, I teach on all machines.
Roma