[firstplanthendo]

There are some theft and risk concentration concerns, along with potential feature problems (accidental card selection change), but this would be great for credit cards rewards hacking- a lot of cards have different bonus areas.. 3x-5x points/cash back on different categories, like dining, gas, groceries, travel expenses, specific department stores, etc. This would easily allow you to maximize your rewards without having to carry around all the different cards. 2x-4x extra back means this will pay for itself pretty easily.