Is this an idea for a alternative coin or something? I only ask this because the amount of double spends under normal circumstances is zero. I think the only real double spend happened during the blockchain fork.
I wasn't thinking too much about alt coins: the idea was that currently we're telling people they cannot use bitcoins for immediate transactions, and I just wondered whether anything can be done about that.
I might be wrong but Bitcoin is not suffering from any double spend issues and the developers are best focusing their efforts into fixing real problems with Bitcoin.
However if your idea can be incorporated into a alternative coin that did not require massive amounts of useless work to support the security of the network, then you might be onto something...
I think we should keep in mind that if double spending becomes an actual problem one might do something about it. An alternative coin for studying it would be interesting, but I personally don't plan to implement one now.