To answer the question posed:
Trick question.
According to Randy Homes Farley there is no imbalance in using 2 part WITH the addition of the third part.
Full details about 2 part and the science behind it are available here.
http://www.reefkeeping.com/issues/2006-02/rhf/
If you wish to debate RHF and 2 part I highly suggest that you take up the debate on Reef central in the chemistry forum.