It would be nice if it came out in a large format, the artwork really would benefit from it. Bigger than DH's omnibus size I mean.

Even if they are able to with the licensing agreement I wouldn't count on it. It's a fairly long series to omnibus considering there are scanlations online. I'm sure Dark Horse is aware of the fan-translation-purist element in western manga fandom and considers it when planning manga collected editions. Even if you crammed three volumes in an omnibus it would still take ten books, if they started the line I doubt they would sell enough to warrant finishing it. I think the same is true for Berserk.

Has there been any manga in the Dark Horse omnibus line other than Lone Wolf & Cub?