What sort of a firestorm would I start if I suggested that the SPF GT40s should be considered differently regarding future values as compared to any of the others save the Holman Moody & the Gelscoe's? This is not to suggest that any of the other replicas are somehow inferior but rather that the SPF tag holds a certain cache in the market that the others do not.
The cache of SPF occurs because they can use the GT-40 name and that they are manufactured (more consistent build) and most have engine assembly by Dennis (generally well sorted).
Value is always the inflection of agreement between a willing buyer and a willing seller, but generally...
Regardless of make, the more accurate the car the more the value. Webers +, correct engine +, no extraneous modern bits like mirrors and such + because it broadens the appeal of the car. The less accurate cars and the "self builts" will not be worth nearly as much as they become more personal taste.
As a CAV owner I personally believe the CAV is a prettier car in the flesh, but is certainly less accurate a replica. Rear is too low, front nose has the hard edge (I had it ground away on mine), stainless body, has the KVA line, VDO gauges, etc. It will be worth less IMHO if identically prepared to the SPF because of accuracy.
However, it is a more livable car than the SPF though none are daily drivers.
Again, IMHO, none (CAV, SPF, RCR, etc.) will ever be real collector cars as they don't carry any provenance.