Hi,
This is an interesting subject. When I dry needle trigger points, I tend to do so only when a patient reports abnormal function. I agree that the literature has little to offer on the reported findings in Travell & Simons, and I cannot offer anything further with a specific evidence base. However, there is literature on feedback loops and muscle inhibition following pain or inflammation, which may be relevant to how trigger points actually influence muscle tension. Post needling muscle relaxation is frequently seen clinically, but I agree that this is anecdotal rather than scientific (at present).
Latent points are more difficult to deal with than active triggers, simply because they are latent and harder to find / treat.They may well have an effect on muscle behaviour, even if it is subtle. Would a large more active trigger overlap and mask a less active trigger, and the less active trigger only show up once the predominant point was successfully treated? Possibly, but again I have no proof.
The lack of comment on this topic is likely to be due to the fact that this is an evolving area, and your post was related to actual research info request.
Sorry I cannot help you further.
MrPhysio+