Are there any weaknesses in the EFAS/IFAS classification system?

Answer 1

Of course. Anytime you give subjective scoring (weights, and scores) on an intangible item that weighting/scoring system at that time might turn out to be different at a later time or in different circumstances.
The weakness is that it is trying to put a number on the value of something that time, place, and circumstances will in the end determine. If one had a crystal ball, EFAS/IFAS would be very valuable.