TeguTalk.com is a great place to learn from experienced Tegu owners (I'm Toby_H there)...
"Stastically", Argentina Tegus are much much much more tame, or easier to tame, than Columbians...
Reds, Blues, Black & Whites as well as 'Extreme Giants' are all "Argentinian Tegus"...
I have seen very aggressive Argentinian Tegus. Though in each case it was due to poor living conditions. Essentially, any animal that lives in constant stress will not be a friendly animal.
Yet, a well cared for Arg Tegu is very easy to make puppy dog tame. Their care is quite easy, but there are a few key points that you cannot overlook.
I could go on for hours about how sweet my '08 male Arg Tegu is. It's never bitten anyone, it free roams the house frequently, it free roams outside without running off, it visits local pet stores frequently, it tolerates children petting poking and pulling at it without any fear or threat. People are constantly shocked by how friendly he is.
Taming my Tegu was super simple. I handled him frequently and politely giving him absolutely no reason to fear or dislike me. I gave him a large enough cage with time to free roam (much more as an adult than a youngster), proper food, light and water...
I confess, raising him I feared I wasn't doing enough to make him as sweet as I hoped him to be. But now as a young adult Tegu, I honestly could not imagine how he could be sweeter.
...okay, if he learned to clean up his own poo, he would be sweeter... but other than that he's perfect!