Don,
Foot-rise (particularly when used by the lady dancing backwards) has a blocking, jamming effect on the person using body-swing, when dancing forward. Yes, the person using FR when dancing backward would not be able to control the subsequent compression and stay "long" on the supporting foot because the person dancing forward would force an uncontrolled lowering. So, NFR contributes to staying long on the support foot because it contributes to togetherness and "control" in the partnership for the reasons I listed but it does not embody the entire concept of staying "long" on the supporting foot as your view seems to imply. SocialDancer also makes this point and I'm in agreement with it.
Staying "long" on the supporting foot is not fully expressed by the observation of getting to the heel "early" and any perceived "pausing" not because I refute that this is what is actually happening with that particular foot when observed in isolation but because "staying long" is a much broader concept than that. Staying "long" on the supporting foot is also a mere observation (perceptually or otherwise). Therefore it must not be a conscious goal or dancing intent in itself. However it manifests itself through a combination of the use of body-swing, controlled weight collection (elements of NFR) and the usage of the supporting leg in "anchoring" and powering the swing to produce a far more "pleasing" musicality.
It is possible to dance with NFR correctly and still not get this concept of "staying long on the supporting foot".