No need to justify anything - if you will still use it (ie at classes) or to pass along to someone in the family, or as a "critical spare" when the other one is in the shop ...... Can you tell I can justify anything?
I still have my Singer 401, a Featherweight, an Elna 740 (primary machine) and I just got a Husqvarna Designer Ruby Royale for embroidery - I would gift the 401 to someone who truly wants to start into sewing, at least that's what I tell myself, but then I talk myself out of it because it's such a work horse! So good for sewing canvas etc and I've had it for 45 years, bought it used!