If you want a real competitive tournament, make the level requirement 30, which is what I think Lan OC was aiming for.
Even though i'm only level 25, i could see the level 30 requirement making the tourney a true battle royal! Even if a person is more skilled than a level 30, being 5 levels behind with all the runes, and extra abilities that it grants, it really makes for an uneven fight...
I like how NeXuS always does the random teams, so i'd assume that's what they are going to stick with.
I'd have no problem running a unofficial tourney with some brackets to encourage some inter-LAN play. I know we put up a good fight at LAN OC, but due to not fully understanding the bans/picks/trade system in game we lost one best players character because I had last pick and didn't own that character.
I have seen on other forums that Riot can be contacted to get the Tournement software so that there can be all characters available, everyone is level 30 to allow for max runes and abilities to be used... Might be a cool sponsoership for future lans!