The only other fighting tournaments in the World that compare in brutality are Muay-Thai tournaments in Thailand.
SUCKMYMUSCLE
Umm - you may not be aware of this, but from the late 1960's through to when I competed in the early 90's (and perhaps even today, although I suspect the rise of MMA has killed it off), there was quite a large fighting circuit in South East Asia, open to all styles, that allowed bare fist or 'covered' (ie - very light foam knuckle shields) striking to all parts of the body excluding the eyes and the back of the head. Throwing was allowed and strikes to a downed opponent were allowed (no grappling though - we all thought we didn't need it and it was thought that good technique saw you standing or in a dominant striking position after a throw). Groin strikes were legal. Joint attacks were legal. In this sort of format I often saw the thai fighters struggle with the larger range of offense than they were used to - and yes - the fact that these fights were often more 'brutal' than a typical Muay Thai match gave them some problems occasionally.
I'm taking nothing away from the MT people - they are awesome and have a fucking fantastic art and usually did very well in this format. In my very first tournament I was knocked out cold by a thai dude climbing on my leg and kneeing me in the face - I have the utmost respect for them - but to say nothing was more brutal than Muay Thai bouts until Vale Tudo reached the masses is not correct.
As far as the Smashing Machine goes - it is the best documentary I've seen. Goddam perfect and so poignant - especially his part at the end with Coleman. And if you listen to the filmmakers commentary, he says something along the lines of it being a film about a man who was the very best in the world at what he did, but he didn't really enjoy doing it all that much. What an incredible way to look at Kerr.