Do I really need a dual boiler, or is a single boiler / thermoblock enough?

Specialist communities are pretty clear: if you mainly pull straight espresso, a well-implemented single boiler or thermoblock (like the Barista Pro or Touch) is fine. If you pull back-to-back milk drinks and want zero wait between brewing and steaming with cafe-grade steam pressure, reviewers strongly favor a true dual boiler such as the Breville Dual Boiler in the Dynamic Duo package.