Terc, the legitimate question you have posed is one that has never been settled. It has certainly been hotly discussed for over a hundred and fifty years. The proponents of back action locks insist that not having to make cut outs in the action for the lock results in a stronger action. Those who promote the bar action lock point out that wood hasn't been removed in the weakest area of the stock, the wrist. There are also lesser arguments over the merits of the spring being forward or behind the tumbler. Personally I think the debates are nothing more than attempts to support the particular design adopted by the maker and traditions that go back centuries. The bar action predates the back action by a couple hundred years. Great food for thought though.
PS: I think island locks are just downright sexy!
