This leads to a more general question that for me always hovers in the background -
These things are grey areas because there is no law (regs, advisories, court cases, etc, that interpret the code or Treaty, etc). There will be no answers until there is such law. What is the responsibility of the TP in these situations? What is expected of him/her? And if the TP is questioned by the IRS on one of these gray areas, what does the IRS do? how does it determine if TP got it right or wrong (if there is no right or wrong)? And if it determines that TP got it wrong, what are the consequences?