Not necessarily. I usually buy a cardback paying 7.00 BRL. If I use the same amount to buy packs, I'll recive only 2 packs.
So, 7.00 BRL (1 cardback) + 500 gold (5 packs) is better than 7.00 BRL (2 packs) + 500 gold (1 cardback).
I'm realy disapointed. I love cardbacks but it's a bad deal for me only use gold.