So if we have our trust lists set to level 2, then everyone on our trust list is level 1 and then everyone on our level 1 has their own level 1s, which would be our level 2, so in other words our trust would not be affected by changes in DT1, only by our changing our trust list or those on our trust list changing their level 1s.
If you set trust depth to 2, you will likely be ended up trusting the feedback of most of the forum users.