Gold coated brass speaker spades

Brass is just copper with some zinc tin for hardness. Copper is a better conductor but you got better ears than me if you can tell the difference.

It’s how they sound to you in the end.  If the Tara cables sound better than comparably priced competitors with copper connectors I say go with Tara regardless.  Still surprising they’d use brass though because copper spades just can’t add all that much to the final price.  Not a good choice for a company like Tara IMHO. 

What makes you think they are brass?

Direct from the source:  I inquired and Tara told me Brass with Gold Plating.

They do not offer a chance to upgrade.

Brass might be cheaper than copper, but, do we really know that it is bad for sound or that it is a bad choice to do cost cutting on the choice of spades vs. cost cutting elsewhere?  Presumably, only the very top models of these companies represent no cost cutting/no compromises in the execution.