Having spent the last winter testing most every connector on the market, I would agree, and disagree. Yes the connecter plays a part, but the cable layout and material selection proved far more significant in my testing of over 200 designs and wire combinations. If you check out my DIY Interconnect Review you can get more detail. I was quite surprised to find the very affordable Eichmann plugs to better (to my ears) many of the very expensive old line connectors. The WBT NextGen are a bit more open than the Eichmann, but the Eichmann proved to my ear to be are neutral as any connector.
I also found the pure silver connectors to be very open and fast, but I am not a huge silver fan. I just recently tried the Furutech Rhodium RCAs and found they nay be the best yet, very open, fast and transparent, yet seemingly quite neutral.
As for mixing materials, well
Im not quite as sure about the importance of matching as you sound. I think its a taste thing, yes; but more so its finding the right combination sonically. It may be that one conductor is best with one material connector, but as I said, my experience is the cable design and conductor material far out weighed the connector.
Jd
Jade Audio