I have a suggestion, but no idea how image boards in general or e621 in particular work. So I'm sorry, if this is a silly, impossible idea.

If someone posts a higher quality version of a pic(higher res or something), the lower quality one is usually deleted. But then comments, tags, favs etc. are deleted too. Is it possible to add a "Flag for Replacement" function? One could upload the higher quality version, then flag the old one for replacement, a mod looks into it and then merges favs, tags etc.

Or are you already doing this, if someone adds a higher-res version of a pic? Maybe it wouldn't need an extra function at all.

sounds reasonable, but the mods don't like working extra or adding server load

Maybe if we all send mellis a dollar, he'll do it.

It won't be extra work (for the mods, not the one who programmes the function, of course).
For each flag for replacement, there would be one flag for deletion less.

We should still send mellis that dollar, though.

if it add strain on the server, no matter how small, it won't fly, since they have to pay for them out of their own pocket per month

comments and tags aren't deleted, they just stay on the page the deleted post was on
and faves get moved to the parent post when a post is deleted (if it has one)

There's a post already for this: http://www.e621.net/forum/show/5089

Riversyde said:
comments and tags aren't deleted, they just stay on the page the deleted post was on
and faves get moved to the parent post when a post is deleted (if it has one)

Nice to know, so the function is already there.