Yes you are correct.
The Internal market also trades with HBD pegged at $1 regardless of what tge actual price of HBD in the market is (if I'm not mistaken).
Say the price of HBD is $2 and HIVE is $0.2, you should ideally get 10 HIVE per HBD. But that would mean someone on the internal market has to sell HIVE at 10 cents for you to get 10 HIVE per HBD as HBD is still considered to be $1, which is very very unlikely.
In this scenario, where the price if HBD is significantly above $1, you would get the best rate on one of the larger exchanges, blocktrades, bittrex etc.