I am curious. What is the deal with those uncompressed editions? Is this higher resolution renders or what? Now, that would be interesting.
(And I do hope it is not meant literally, because png is a compressed format, just not a lossy one. Having bmp would be insane!)
Because, if it is exactly what it says on the tin ... why bother? Unless the compression is done very poorly, one should not see the difference. Especially with rendered images. Lossy image compression is bad for 2d (comic) art, because it can fuzz the lines. Here you have no inked lines that could fuzz.
Oh, and if it is both, uncompressed and higher resolution ... uhm ... what file size increase are we talking about?