Earlier, I describe the use of BerryBoot with an external USB HDD with a RPi (1) B+. To be honest, this was a terrible user experience. While everything worked, this setup was tantalisingly slow. I mean really really slow.
My assumption is that the USB2 implementation of the RPi1B+ does not reach USB2 speeds, not even close. Presumably the USB ports a run by the CPU, which in itself is relatively low power already. Consequently, I abandoned the idea of running the RPi1B+ from a USB drive.
As an experiment, I used the exact same external USB-HDD and microSD-card with my RPi3B+. What a difference! This setup really resembles a usable desktop computer.
In my experience, the Raspberry Pi 3 B+ appears to be able to run the USB2 ports at USB2 speeds.
While booting and running of the microSD-card appears to be a little bit more snappy, the combo of BerryBoot and the externally powered 3.5" HDD on USB2 delivers an acceptable user experience.
The obvious advantage of this particular install is the amount of storage available, in my case more than 300GB. The amount is only dependent on the HDD in the enclosure.
