As far as darkfriends... I'm not sure. I mean, on the one hand, if the Dark One wants servants everywhere, there's nothing really preventing someone from pretending to follow the Way. And I guess if a Tuatha'an were really committed to The Way but wanted power or something... I don't know, it does seem like the Tuatha'an mindset would be really at odds with service to the Dark One. That's an interesting question, actually... What would a Tinker Darkfriend look like?
Anyways, what comes to mind when I think of the Way (especially as it was followed by the Da'shain Aiel) is Jesus' "Sermon on the Mount." In particular, the whole "Do not resist an evil person" and "But I tell you who hear me: Love your enemies, do good to those who hate you, bless those who curse you, pray for those who mistreat you. If someone strikes you on one cheek, turn to him the other also. If someone takes your cloak, do not stop him from taking your tunic. Give to everyone who asks you, and if anyone takes what belongs to you, do not demand it back."
Of course, I think that contemporary Tuatha'an are more likely to resist an evil person (in the form of running away), and although it's pretty clear that their reputation for thievery is largely undeserved there may be some truth to it. But at one point it was said in the books that you could strike a Da'shain Aiel all day and he would only ask what he had done to offend. I think the Way, in its pure form, requires more courage than the Tuatha'an bring.