Susan,
More than once I have had to go to my backup machine, so you are smart to have one available. Often I have had regular thread in one machine and monofilament in the other. It will also give you a machine to carry to classes. Also, I don't like to take my primary machine out of the house. I teach 4Hers and having a second machine set up in my sewing room works for me. (Would you believe that I have an 11-year-old student who quilts 10 stitches to an inch? All I do is draw her a line. She's a natural, puts me to shame!)
My husband accidentally dropped my secondary machine once and although it is scarred, it was repaired satisfactorily.
Happy Easter, Suzanne