Wirelessly posted (Mozilla/5.0 (iPhone; CPU iPhone OS 5_1 like Mac OS X) AppleWebKit/534.46 (KHTML, like Gecko) Version/5.1 Mobile/9B179 Safari/7534.48.3)
I just got a battery case for my 4s and it well guarantees any given full day of constant use with no recharging, but if you prefer a different device for different tasks then I guess that works.