It turns out that the version of AdvancedFirmata I included with Breakout v0.3.1 has a bug. It’s fixed in the latest version of AdvancedFirmata that is available separate from Breakout here: https://github.com/soundanalogous/AdvancedFirmata.
I’ll push a new version of Breakout tonight that includes the updated version of AdvancedFirmata.
The only thing AdvancedFirmata currently provides that StandardFirmata does not is stepper motor control.