In situations where the ambience cues are subtle or absent, having room reinforcement would likely be beneficial. But in cases where the cues are already strong, reinforcement could become excessive.
Cbw This is a good point. To the extent that the ambient cues of the listening room resemble those of the recording space, playback in the listening room will reinforce the ambient cues of the recording. It is certainly possible that, for some recordings, that reinforcement could be excessive. In the worst case, the ambient cues of the listening room would, in effect, "double" the ambient cues of the recording. In light of this, designing a listening room with the intention of reinforcing the ambient cues of one type of recording space must be approached judiciously.
with weak or absent cues, and hard-to-duplicate room acoustics, electronic enhancement may be the way to go.
The idea of creating listening room ambience by electronic means is appealing in theory. In practice, however, the limited experience I have had with professional reverb processors from high end manufacturers was not favorable. Although they were much better at creating ambient cues than the DSP processing typically found in consumer components, they were nevertheless, to my ears, artificial sounding. Because of that, I am skeptical of the electronic approach to creating ambience, at least with the current state of technology. I have far more confidence in the results of controlling ambient cues through listening room design.
I'm not sure how much the playback system's coloration is an issue. Assuming the system is good enough to produce playback with a convincing live or nearly live sound (as judged by the system's owner/primary listener), it seems unlikely that the ambience cues are going to be distorted to a point that they become an impediment to a "you are there" experience.
I agree that the equipment is less important than either the recording or the listening room in determining ambient cues during playback, as I indicated in the descending order of importance in the OP. However, I believe that colorations in equipment can be a real obstacle to the presentation of ambient cues during playback. I became convinced of this when making component changes in my own system that simultaneously resulted in (1) greater neutrality, judged by independent criteria; and (2) greater audibility of the ambient cues of recordings.