I believe the proof is in the fact that EPDM and Fibreglass are never seen on commercial projects and are predominately used on residential roofs.
Do not be fooled by the “old felt” saying used by people who install systems that can be taught in a days course.
Built up felt roofing is a proven system that’s when installed correctly ( staggered joints, bitumin bead at the laps) come with guarantees of 25-30 years.
We are approved installers for Bauder, garland, iko, sika, Triflex, Kemper, Polyroof so our knowledge of the systems is very vast.
Everything has a purpose but unfortunately there systems (EPDM, GRP) are DIY and will never be up to scratch with the liquid systems like Triflex or Kemper.
So to answer your question, use felt... but make sure the installers are approved contractors for the material manufacturers first and not buying felt from B&Q