I do not know about the ones you posted your link for or how long they will last. I do remember that a few years ago a member on the Excalibur forum made something like that which I believe bolted to the riser and faced the string, close the the rail. Yes it did quiet the bow without cost of FPS because it only contacted the string after the arrow was released. But I remember Bill Troubridge saying that he was very interested in it, but after testing it, it wore out very fast and then was actually causing more noise then if you did not have it in use.

I believe that on regular bows (70 lbs or so) that they will work great and last longer but with crossbows (150- 225 lbs), the force and power eat the dampners (pads) like in the test that Bill did. But untill crossbows become very prominit and alot more of them, the companies that make these things will just not develop then for crossbows, just not enough demand to get their investment back. I sure hope that the two in the link you provided work and last as it would give us shooters more things to tinker with (like we actually need it LOL ). But mnore options are better.

The trouble is getting the pads stiff enough to last with the force of the crossbow, but still soft enough to absorb the viberation in the string. I do not know what are used in the link you provided, but the one tested by Bill, I believe was just the normal compound pads. It might be worth a try to test them, either the STS system or thw link above, but me personally, I will wait untill it is well proven to work and last.