We're talking nth degree stuff here in my opinion.
If you're happy with your setup, you will see much more variation with coffee and grind quality. All of this assumes that you are consistent in what you are doing as well.
You might go to a Duetto because you plan to plumb in one day or prefer the quietness of a rotary pump but a well configured machine is ultimately a well configured machine and will produce great shots when everything comes together.
Assuming that your grinder is up to the task, you'd be upgrading because you want something different. I guess one bonus is that a lucky CS'er might score a beautiful pre-loved machine at a fair price.