I had already looked at the the Sanguino website.
There is a page on the site on “the differences between the Sanguino and Arduino” that I hoped would help. But it avoids mentioning the issues that prompted this thread, i.e. Arduino playground code that accesses resources like direct port IO not working on the Sanguino.
The board looks to be welcome addition to the Arduino/Freeduino ecosystem, but as this seems to be commercial venture and is promoted as “compatible with the Arduino software”, I think the Sanguino distributors should clarify areas that may not be compatible with widely used (and not necessarily official) code in the Arduino playground. And ideally provide advice on porting code that accesses resources like direct port io/ timer registers, PWM pins etc so that people producing code for the playground can help users get up and running on the Sanguino.