Excellent ligs that I use on sop, alto, tenor and sometimes bari. They are very easy to use and don't dampen the sound at all.
All of the three plates work well for me and the Vandoren descriptions of the different sounds are pretty silly really.
The downside for me is the cost - they are over-priced here. I have bought a couple of mine used and one even came free with a decent used mouthpiece I bought from eBay.
"Plastic version" just means a plastic mouthpiece cap rather than metal to keep the price down a little. They have a nice rubberised finish to the plastic cap but they aren't very strong.
I have used one on my Alto for the last couple of years. They are well made and are very easy to use and to adjust. I have the plastic cap which so far has not cracked. I also agree that the individual plates are a bit of a gimmick and I can't detect any difference in any of the 3 supplied. I suspect you won't be disappointed if you purchase an Optimum provided you are happy about the cost which is a bit OTT.
I use one on alto, bought second hand-don't bother changing the plates, but it's easy to use, looks nice, and clamps the reed to the mouthpiece. Having said that, I bought a mouthpiece years ago which none of my ligs fitted-a cable tie worked fine !