Not sure about Samoans unless I wanted a great defensive line to demolish an opposing offense but I certainly agree with you about the Ghurkas and the Sikhs. They are some of the baddest soldiers on the planet. The Gurkas tend to be little guys while the Sikhs are usually big dudes. Good high-low kick butte weaponry!
All of the three groups that I mentioned have a reputation for even temper (up to a point), good humor (even if they are scowling), tolerance, and sheer kick ass warfighting skills.
/johnny