Apple is losing me here.
Why having a crippled iPhone 5S as a 5C? As if Siri and finger sensors are a deal breaker to me?
Why not just having a 3,5" screen for the 5C? 3,5" is a cute size and a REAL differentiator. Some value screen estate, others value portability. Having said that, I wouldn't make the screen bigger than 4".
And why not calling the 5C, the iPhone mini? Like iPad and iPad mini. Mac and Mac mini? And hopefully soon, iPod (= Touch with 4"...