[mdavej]

Depends more on your eyesight and aspect ratio. Those two screens may very well be the same aspect ratio. A4 is close to 2:3, the aspect ratio of an iPad. So even though the iPad is smaller than 14.4, the page image may actually be the same size on both. Personally, I have a 12.3" screen that's close to 2:3, and I wear glasses, so it's quite comfortable for me to read. I had a 14.4" before, but it was 16:9, resulting in the exactly the same page size as my smaller tablet. Anything smaller than that is hard for me to read.