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E-book might go mainstream, but so far, the quality is unsatisfied, it has a big problem about the huge file size. If you want to take the image quality, the size would be too large for comfortable reading.
So far, it works well a kind of showcase, I suppose. You can try the book, then if you like it, buy the actual book. That would be ideal - problem is, in that case, the number of the copy must be less than now, it means the sales might not well enough to pay all the cost. It's difficult situation for manga industry, oh well....