I think that even though teams and individual players are withholding decklists it is still quite easy to see their newest tech. If you actually watch them play in a tournament you can probably see a good portion of thier sideboard or maindeck tech slots. Even reading other players reports they mention cards played against them and stratagies that shut their decks down.

The idea of having a deck completely concealed is flawed. If the deck ever sees any play outside of the team or playgroup someone is bound to find out. If a deck is competative and has secret tech in it the team has two options:
1) Conceal it from all the other members of the T1 community or
2) Wait until an appropriate time and play the deck in tournaments causing a high chance of having your card choices revealed.

The first idea is the most harmful to the community. The second idea I see no problem with. It is in the team's best interest to win with the tech they came up with. After it's been played a few times it really isn't very hard to figure out thier card choices and they would have no reason to conceal them any longer.