In reply to KTT:
I disagree with the arena for this kids' tournament. It shouldn't be held in the same venue as adult MMA. I was very involved in MMA when I was younger and even as a fighter and ring man I didn't enjoy the atmosphere of most of the venues, which was generally very drunken and rough (there were often fights in the crowd). A lot of the people who showed up had no interest in martial arts but liked the 'tough' idea of no-holds barred fighting (as it was called back then). I wouldn't take a kid into that environment.
However, I would endorse kids learning grappling and striking martial arts from a young age.
On the other hand, that I think that the pure Japanese martial arts are much more appropriate to teach to children because of the moral training that has been deliberately incorporated into their syllabuses. Judo was developed as a way of toning down the more dangerous aspects of ju-jitsu whilst preserving a fighting spirit and Jigoro Kano meant it to improve the mettle of the Japanese youth. Most judo clubs I've trained at, for example, had rigorous rules that were aimed at preventing bullying and misuse of strength, and bashing someone weaker than you was very much frowned upon. I'd have thought Olympic and Greco-Roman wrestling (and probably Lancashire catch also) have similarly enforced rules.
In my experience of Brazilian jiu-jitsu and MMA the 'moral' behaviour was less enforced, with more emphasis being on transmission of the skills to fight. Beating someone up in training is not encouraged, but there was never any sort of moral guidance that would make you think twice about using your skills in public.
In my judo club you didn't learn locks and chokes/strangles until a certain age (I started at about age 6 and the focus was on throws and pins until after about age 12) when you were deemed mentally mature enough to know the proper application of these dangerous ju-jitsu techniques.
In short, I don't think little kids should learn how to apply locks and strangles/chokes, as I don't think they'd know not to use them in fights with their mates. So I'd even censure ADCC-type competitions (which I don't see as particularly violent) for kids until after a certain age.
As for the cage, it adds to a lurid spectacle of the children fighting. I'm pretty sure the cage was first used in UFC for example as marketing and to emphasise the 'brutality' of it in terms of salesmanship rather than as a safety measure. I'm pretty sure that is retrospective justification. Having said that, I preferred fighting in a cage to in a ring as I had seen some nasty tumbles under and over the ropes eg in Pride.