There is no interworking problem between a US Galaxy S3 and a Pico.
The interworking bug between an international Galaxy S3 and a Pico was fixed: no more need to use a USB 2.0 hub.
With my US Verizon S3 + OTG cable:
- FiiO E7 - works
- Pico - doesn't work. What am I doing wrong? Could it be I have an older model Pico Serial #2xx? (it works with a powered hub, though)