I have bought a couple of recent sterns second hand. My thinking is that I am getting lots of people over to play tournaments, introduce beginners to pinball etc. A machine that is 20-30 years old breaks down much quicker, plastics parts are brittle, metal parts are worn and fatigued. So I want some recent machines that will take more plays and not require so much of my time keeping them playing.

You can have that with old an new machines.
Do the work up front and the older machines are just as reliable, especially in a home environment.