Manual espresso machines are great and you would not be disappointed buying one! The main advantage of one with a pump is how much more repeatable the entire workflow is in terms of preheating and maintaining pressure - you don't need to repeatedly pour and purge water from it, and the pump will output exactly the same pressure every time.

In case you have 26 minutes to kill, here is an interesting video on the subject of group head diameters.

https://youtu.be/jTAkb-dCFro?si=xYffYaVnOQkZB0ZH