When a young man in the later 40s and 50s, ligatures were always metal with two screws to the right, tightening the reed on the mouthpiece. I am tlking about the Eastern US.Then in the 60s, the Bonade ligature made its entrance, having two rails which aligned the reed correctly, or the way you wanted it. Then a bit later, a clarinetist took a pair of pliers and just ripped out a piece of the Bonade and turned it around, thus the reverse Bonade,then manufactured to the reverse with the screws on the other side and top still used by some currently. The mid 70s brought on the Rovners and their various textures and materials. The interesting thing about these is that the variations are really much less than forthcoming to changing or enhancing clarinet sound.
Nobody can play two ligatures with the same reed simultaneously, with the reed in the exact same place, so who can tell how it actually sounds.But one may feel something different, although different folk may have different opinions. There was between these somewhere a neat thing called the Harrison, expensive with all kinds of funny stamping in the shape of an H. This was of course discontinued, and then brought back by another company. There are of course the VD optimum which uses different plates to change the sound or to facilitate certains points of technic. The Daniels has eight plates , I think, and there are all kinds of revelatory pieces of chozerai(Yiddish:superflua) to put in between the reed and whatever is holding it on to the mouthpiece. There are evnen more exotic(read epxpensive) ones around, but nobody can prove their prowess in doing what?Nobody knows. Really, Its all feelings…..just like the song.
I have always used a ligature so that I can change clarinets , you know from Bb to A, without the thing coming apart in my hand, the reed on the floor, me bending down, picking it up and missing the entrance. Afte that it becomes another game of the Emperors New Clothes.
It is always a little sad to read young players listing their clarinets, their reeds, their setups, their ligatures, and of course, the clarinet and model number.
What in the world does this have to do with music? As someone has said above, it has a good deal to do with money.
Teachers should not perpetrate this kind of behavior.