I am a very new 3d-printer user and so a dummy and reading many forum topics to increase my knowledge about the Vertex. One of the issues I read about is printing with soft filaments.
I had some stupid thoughts about the filament extruder motor. I understand that this motor, if moved to the printhead, will become more of a pull force instead of a push force on the filament. But a motor on the printhead is a heavy load to carry.
What about leaving the existing motor on it’s place to push the filament and use a second motor to pull through a flexible shaft (You can buy this for your d-i-y drill, but also the dentist is a flexible shaft user 
Then only the filament pulley system has to be mounted on the printhead.
If you let the two motors run synchronous you become a push and pull escort for the filament and maybe it is helpfull for the soft filaments?
Let me know if I am totally nuts.