Despite that, Lynch, who led a presentation on the digital publishing landscape at the London Book Fair last month, admits dedicated e-book readers have a limited shelf life. 'The e-inks are facing the danger of not being able to keep up the pace. As technology continues to advance and evolve, readers have higher expectations about their user experience - and there is the issue of device overload. Consumers don't want to be carrying around multiple devices, all having different functions.'

So worried is Amazon about its Kindle that, despite releasing a 'touch' version this spring, it has already converted to tablet tech with its US-only (so far) Kindle Fire.

Not everyone thinks the e-reader is in trouble. 'By quickly dropping price, as well as size and weight, and rapidly adding e-books to their catalogues, e-book readers like the Kindle have stayed not only relevant but thrived,' says Mike Haney, chief product officer at Mag+, a platform for publishing magazines and books on to tablets and e-readers. 'The success of both e-book readers and tablets seem to have fed each other by convincing consumers they need some kind of device that is neither phone nor computer.'

When tablets such as the iPad are slashed in price and size, they'll begin to erase the e-book reader's advantages. But Haney says e-ink style screens - which mimic the appearance of ordinary ink on paper - will continue to live on, as some people prefer that reading experience to a backlit-LCD screen.

'Reading the text of a book of fiction is an immersive and emotional and cognitive experience,' says Desmond O'Rourke, course director MA Publishing at the London College of Communication. 'This demands engagement without interruption or distraction from glare, or sunlight, or screeching sound effects or pop-up advertising and e-mail alerts.'

O'Rourke prefers the Kindle over the iPad for long-form reading, but is yet to find a digital substitute for art books and magazines. He also points out the iPad's media-rich capabilities, such as the Faber & Faber app of T.S. Eliot's poem The Waste Land. 'It's a good example of how poetry can be brought to another level of understanding by using a device that goes beyond the boundaries of the e-ink, e-book display device.'

If the trend is towards 'books' with video, music and animation, the chapter-and-verse future is tablet-shaped. 'Books are no longer just something you can read, they are becoming interactive,' says Lynch. 'Tablets are able to offer the flexibility of multiple language options. There is a huge market for this, particularly in China.'

Textbooks are becoming available with interactive graphics, and although newspapers and magazines can be read on a Kindle, digital magazine apps are more common on a tablet.

What of the practical differences between an iPad and an e-ink e-book reader? I recently took both an iPad and a Kindle on a Hong Kong-London return flight to see how they fared. I relied on the iPad initially, and although reading an e-book proved easy and relatively comfortable for an hour or so, after six hours I felt like I'd been staring at a computer screen all day.

Which, of course, I had. I also got less reading done than I'd planned (iTunes was on most of the time, and I succumbed to the temptation of a film or two).

Once in Arrivals, I had tired eyes and a sore neck and completely flat gadgets. I swapped to the Kindle to finish an e-book I'd started on the iPad, and read it not only while away, but also on the return flight.

It's lighter - just over 200 grams - and with images, bookmarks, text-search and free worldwide book downloads, it has the added advantage that you don't need to take a charger in a cabin bag.

The tablet has instant all-round appeal, but can the Kindle be beaten for the pure experience of reading?

Before we settle on one device being better than the other at 40,000 feet, do remember that neither can be used during taxi, take-off and landing. You'll not beat a hardback for that.