MF and CF have lower firing current than ML. I have used all three. The MF only had a difficult time with red propellant from Aerotech. It may have been old propellant. I finally got it to light with a homemade igniter that burned and little longer.
If I am just dipping cti starters for airstarts I would assume it would not matter or does the pyrogen itself have a hand in the current requirements? Thanks for the info!