A PID doesn't change the design limitations of the Silvia; 1) You can't pull shots & steam at the same time. 2) You have to wait after steaming for the boiler/group temps to restabilize before pulling more shots. A PID impacts intershot temp stability, not intrashot temp stability.
Upgrading from a Silvia to any other SBDU machine is a lateral move, not really an upgrade. You might get better intrashot temp stability, but the limitations of a SBDU machine still exist.
If you wish to upgrade to better intrashot/intershot temp stability you need to look for machines with saturated groups and larger boilers. If you want to be able to steam and pull shots concurrently, and pull shot after shot without waiting, you need to upgrade to HX or DB machines.
Basically, I'm saying first define you're needs, then get input from users.