Tributaries Speaker cables

Good afternoon to all. I’m looking into buying some good speaker cables and I’m looking at the Tributaries 6BW series. Has anyone used them or using them? 
I would like some help on this matter. Also do I spend the extra money to upgrade to their Model 8 series?


It doesn't seem to say on their website if the less expensive line has copper spades/bananas, but if they were brass, I wouldn't buy them.