Found this site, www.warmack.com, which seems to advocate the "Ian McRae/Warmack" theory, which I personally have seen no evidence for, and sounds very unlikely. Basically, an Ian McRae from Scotland was convicted of rebellion against England and sent to Georgia, where he changed his surname from McRae to Warmack, and got a land grant in 1752. If someone has documentation of this land grant, I would love to see it. I have been to GA State Archives, and could find nothing about an Ian McRae or Warmack. Also, I have seen names change over time, but nothing like McRae to Warmack.
Anyhow, their focus appears to be the Warmack line of William Warmack of Davidson Co, TN. I have done research which indicates this William Warmack was the son of Richard Womack of Goochland Co, VA: http://homepages.rootsweb.com/~reburke/lines/data/womack/ew/lines/Descendants_Richard_Goochland_VA.html
Anyhow, this site says that William Warmack may be the son of Ian McRae/Warmack, despite the fact that Ian has been claimed as the ancestor of John Warmack of Habersham Co, GA (also an unlikely theory), and that Ian supposedly came to Georgia, whereas William Warmack of Davidson Co, TN was born in Virginia.
The www.warmack.com website has a guest book, which I have not been able to sign, but apparently spammers have figured a way to do, since it is mostly full of spam junk. I have tried to contact the site owners, but no luck so far.
I personally believe all three early Warmack lines in America come from Womack ancestors, and that DNA tests would confirm this. Will blog more on this later.