This issue of a softer pad potentially muffling the strings has always concerned me, too. But to be truthful, I can't say for certain that the concern is valid. If Wiley hasn't noticed it, with all his experience with different capos, then I have to suspect my concern isn't warranted. I'll likely try this new capo.
I think we have to acknowledge that we each hear what we hear, and there's no gainsaying what our ears perceive.
For instance: I love soundports for the added volume they put in my ear -- I feel like I'm more "inside" the guitar. Other people tell me they can't hear any difference with or without 'em.
I've tried bridge pins made of different material -- plastic, soft wood, hard wood, brass -- and can't discern a change in sound between one set versus another. Others insist that they can.
I've tried the Tone-Rite on a few guitars but, after letting them run for a week, I can't perceive an improvement in the sound of my guitars. (However, I've only ever tried them on old guitars, which, as others have noted, may have already reached their potential.) Others -- including people whose opinions I very much respect -- say they work.
Conclusion: One size does not fit all.