The feature size is relevant for understanding how the chips progress over time. It's not relevant for a point-in-time purchase, but it's not a marketing thing to ignore either.
The plus means a generation of optimization on how to use roughly the same lithography tech, which can give you a big difference when they're so hard to use.
You can always use your 1nm tech to craft more precise circuits of the same size, packing them better. When it comes to the working chips that are made, assuming some tighter lithography that's equally functional to the previous one, it's only going to benefit.
The plus means a generation of optimization on how to use roughly the same lithography tech, which can give you a big difference when they're so hard to use.