I will make a relatively simple statement here.
Supplementation will always fare better to regain a state that is aimed to correct a deficit/dysregulation, than that which is attempting to achieve a truly supra-physiological outcome.
Certainly the aging process is likened to state of deficit/dysregulation/('disease') and within that supplementation can enable a sound degree of 'correction' to what is a more normal, healthy (baseline youthful) state.
Elevation of NAD+ will retard the aging process, in some reasonably significant, but in no way overwhelming manner. It will allow one to have potentials for a minor extension of QOL and longevity. Healthy and consistent exercise will do same. Incorporating multiple supplementation protocols will push these potentials all slightly further in that direction. I do not think anyone should fool themselves though to think we have as yet stumbled on any of true keys/means, however, the only way to get somewhere is to keep pushing in the right direction(s). This certainly appears a worthwhile direction, but nonetheless one of several.
It may be "Coenzyme #1" oriented, but even so this and all such related modalities will likely just afford a strong nudge of the potentials that are desired. A strong nudge toward a potentially healthier life with any degree of extended QOL and longevity is not a bad thing. The real worth of this 'experiment' will really more so take years to see any worthwhile insight into these factors, but within any reasonable signs of a direction that regains a more youthful state there certainly is the promise of betterment in the desired direction. In the short term only that which seems to act upon such 'deficits' is really likely only that which is going to demonstrate valid 'data'.