Will the Shimano Ultegra 6703 STI shifter shift a mountain bike front derailleur? Or does the new 6703 STI shifter have a unique movement that requires it be fitted to a 6700 front derailleur only?

I am thinking about setting up a touring bike with the 6703 STI shifters. 44-33-20 chainrings on an old Deore DX crank. New Stronglight or TA outer and middle chainrings. Right now I am using a Sora double front derailleur. I am thinking a mountain front derailleur will fit the curvature of the 44 outer ring better than the road front derailleur. Chain and rear cassette will be 10 speed.