Aurotones are the originals, no longer in production. Avantones are the fairly expensive modern copies that have a similar name, and are a similar but not exact copy.
Behringer are bringing out the active C5A and C50A (called "Behritones" - there about to drop in the next few months the C5A is like an Aurotone, C50A is like an Avantone mixcube)and there is a High-end Aussie company called Grover Notting making their own version as well. I had a listen through a mono Grover just the other week and its a beautiful broadband speaker, could happily mix on one of those all day. But I think I'm just gonna snap up a Behritone when they are released (and just hide the Behringer logo)
so, back to your question foge,
For end user headphone translation, then yeah ipod earphones are the way to go, but thats not what your asking for really.
In terms of getting a second set specifically for focusing on mids, setting levels and comp settings without having everything hyped etc, maybe look at a pair of open backed phones (if that isn't what your already using). Closed backed have that bass-resonance thing and can be distracting.
Maybe some open backed AKGs? k240s IIs? (I think thats the correct product name), I thought they were really nice when I was testing phones (went for AT M50s in the end)
Aurotones have the theory that because they are a single broadband speaker you focus on the most important part, the middle, and maybe show problems that the crossover in your 2 or 3way monitors were hiding. But your probably just better off getting 1 mixcube/behritone/aurotone in reality and just switch to it from your headphones when you need to
EDIT: As headphones are single driver anyway (well most are) there isn't really any comparison other then less bass buildup in closed phones