The benefit to the sound clip is that you don't have to modify your bridge and you don't have to worry about getting dents in your top plate from a copperhead. Also, if you travel a lot and use rented or borrowed basses you can presumably just drop the pickup on to any bass and then dial in your tone. In theory this is all great, however in practice it all sort of falls apart.
I had one years ago for my hybrid Czech bass and I found that the tone was pretty much always very thin and that it was super difficult to get the same tone twice. I was always messing with the thing and never satisfied. I tries different rubbers to dampen the pickup, different pickup orientations and positions, different weights, many gain and eq settings. I just couldn't get it to consistently sound like a bass.
I eventually got bridge adjusters installed and dropped in a full circle which was in my opinion about 100 times better. That said, I have upgraded my amplification several times since and maybe today I could coax a good tone out of a sound clip today, perhaps a super high impedance would yield some positive results, however I sold it many years ago...