if anyone does eventually produce a metal case device, this product is a nice option to add a very durable and renewable rubberized coating yourself. It's just like the grips you find on pliers, garden sheers or whatever and you can buy it at almost any hardware store, it's called Plasti-Dip:
http://www.plastidip.com/
I use it on almost all my tools to make them easier to grip. It cleans easy, is really durable, though it can show scuffs and what not over time but all you need do it rip off the old coating and re-dip the parts and it's just like new again. If the metal case was designed with screws holding it together people could do this themselves or pay to have their reader coated on a per-order basis. Anyone can do this, it's a true no-brainer modification.