So if I am understanding this correctly you can't build a balanced deck so you want to switch your deck up when ever you wish with no restriction do you can have each deck only do its one thing and nothing but that one thing fine. Clearly for hearthstone we need to use a completely different rule set for tournaments than every other card game. At this point I just give up It does not look like anyone is interested in a tournament.
In major card game tournaments you are limited to 1 deck and a side board per person. You can't change up decks in tournament just because you brought a deck that is easily hard countered. Making it 1 deck for the whole is the best way to keep everyone on an even field.
The reason I want to keep it at 1 hero and deck for the tournament is because there is no replay system or any way to watch the matches and with limiting it to one hero and deck before so you can't hard counter other decks intentionally. In your example If some does bring a Control Warlock that can be easily countered by a UtH hunter deck they should have made there Warlock deck more versatile other than limiting it.
Now that Hearthstone is in open beta it is time for a Giant Bomb Community tournament! Now first up there is no way to police this unless you stream it or record it. If you choose to participate pick a hero and one 30 card deck for best 2/3 games then report the winnings here.
Be sure to sign up with your blizzard name and number and use the PM to arrange your matches..