I'm currently using a Breville Infuser with a Sette 270wi grinder to make 3-4 cappuccinos/espressos daily.

I'm quite happy with my drinks. However, if I bought a prosumer machine such as a Bezzera bz13 de (as I would like to have volumetric dosing) are the quality of my drinks likely to improve?

Thanks in advance for the input.

Moving to a mid-range machine will likely improve the repeatability and control of extraction which can help you improve your espresso significantly.

Volumetric dosing probably won't do anything for the quality of your espresso. It makes sense in a production (cafe) environment where you've got two drinks and steaming milk all going at once, but not so much with the one-at-a-time craft of home espresso.

I think you'd be much better served by a DB, rather than an HX (with or without PID), if you decide to upgrade.

I'd look at the Breville "BDB" and come back is that isn't your choice in the under $2,500 range.