I'll definitely be buying BitSLV when BTSX is more decentralised and robust, there's a much higher storage cost for physical silver than gold at international vaults, so I will be more likely to move some of my silver portfolio into BitSLV.
With silver though, a large part of current demand is industrial demand, meaning if there was a big shock to the financial system, that demand could plummet short term before store of value demand kicks in but I'm still a silver fan.
I'm not sure how the BTSX system would cope with a sudden re-valuation of gold for example though.