That's true for smaller readers such as the Kindle or B&N Nook - I've had half a dozen Nooks. Now I use a 10" Boox device. I love the thing, but only when it's on the table. It is too heavy and far too slippery to hold. I even stuck sticky plastic table covering onto the back of the thing to make it nicer to hold instead of the cold, slippery aluminium. But it's still far too heavy.

My next device will be no heavier than 200 grams, and will not have a metal backing.

Is that because they're lighter-weight plastic? That would appear to be one of the primary differences between a Kindle (until recently) and an iPad...