I am aware that with the introduction of the Tiagra 4700 groupset Shimano now uses the 11-speed road cable pull ratio also for their 10-speed road systems. Therefore a Tiagra 4700 right shifter is only compatible with Tiagra 4700 rear derailleurs and 11-speed road rear derailleurs.
Because I would like to run smaller chainrings in the front for my 2x10 setup I need to use a MTB front derailleur. Is this possible with a Tiagra 4700 left shifter or did the cable pull ratio change there as well? If not: Can I use a Sora ST-R3000 left shifter from their 9-speed road groupset instead? What are my options? Which MTB front derailleur would I have to use with which road STI shifter?