Whew I wrote an enormous response, clicked the notification icon and erased everything...
For now, this pack is very different from the current Steam version. But an update to legacy owners of the Steam version should be rolling soon. The main difference between this and Steam will be, then, the presence of .PSDs, which allow you to make new variations of most monsters. (Most of them are separated in folders with opacity masks, by clicking on the individual layers/folders and altering the Hue you can make plenty of really neat edits). I plan on releasing further content updates on this one such as new monster variations, and since this one is independently published, I can roll out updates and new content in a much swifter fashion.
I don't know how I'd approach 'loyalty discounts', since any previous sales are information accessible only to my publisher, so I have nothing to go on.
Still, I'm looking forward to feedback, both on the contents of this pack and things you'd like to see in the future! Packs #02 and #03 are on their way to here :)
edit: I noticed that the short description mentions "extra files"; this is a relic from a previous version of the pack and I'll swiftly remove that. For now, it's the .PSDs.