Boxed sets: Only if I do not own any singles contained AND they are not 'Monster sized'. Poor old reader really wheezes on multi-Meg books.

I would rather have a 'Bundle' of individual books (A true boxed set) at a discounted price, rather than a Monster sized Book
Omnibus: It might make production sense from a PRINT run standpoint, but the economics are really not there in e-book (Format for e-book, Split, Ship)
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Boxed sets/ Omnibus (same series) with inconsistent visual formatting between 'books' is just laziness.
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