I bought an M1 MacBook Air in 2025 – but can I resist the M4?

I thought I had this figured out. I was making a hard-headed decision to buy a refurbed M1 MacBook Air with 16GB RAM for half the price of a new M4 one, for reasons I’ll explain in a moment.
But, ironically, it’s because the M1 version is so good that I think I’m at risk of selling it again and buying the shiny new M4 model …