Kimber Kable 12TC vs. 8TC for 15ft runs.

Anyone having experience comparing the KK 12TC vs. 8TC speaker cables? I require 15 ft cables and am wondering the benefits of the 12tc over the 8tc cables run between my BEL 1001 MK5 and Esoteric MG10s. Thanks in advance for your help.
I am wondering the same thing except I need 20 foot runs. Do you know what is the gauge of the 12tc wire? I am using 20 foot runs of Groneberg speaker wire but not sure of the gauge.
12 tc is 8awg, and 8 tc is 9awg
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Thanks all. I purchased a set of 12TC.