The biggest soft issue is how much it would cost to replace your husband with a similarly qualified local person. Salary.Com and a fair number of the site use fairly standard cost of living analysis, which do not take this into concern.
Then there is a trust and political factor -- if they trust your husband he can demand a lot more than what salary.com says. US based companies always like to have somone from the home office watching over and mediating over the overseas operations... and god knows the folks in the local offices need a headoffice person to keep the US folks at bay.
Anyways, at the end of the day what matters is that the company is convinced that they will get a return on investment on the amount they spend... the comparative numbers are fairly meanless when it comes to ROI.