ET3D: I'm really tempted to get this on Comixology, since it offers both convenience and the DRM-free formats. I only bought the base bundles of Humble and Groupees, so I'm still missing a lot of stuff.
madth3: As I pointed out earlier, not all the issues in the bundle have DRM-Free backups. Unless they are unproperly marked in Comixology.
I can confirm that some of the Comixology issues are not yet DRM free; having purchased the bundle there's no accessible direct download link for titles like Chaos, Alice Cooper, Frankenstein, Dresden Files, Mercy Thompson, Red Sonja, Kirby, Monster War, Sherlock Holmes, Uncanny, Warriors, Green Hornet(s), Pathfinder...
It's possible that Comixology may add DRM free downloads at a later time.