FelixC,
I am familiar with P. auriventris but I never have kept one myself. They are definitely not Allen's damsels and you are correct that they are two different species. I believe they have a similar disposition to P. alleni but I have no first hand experience. Some Pomacentrus are very aggressive so you have to be careful. Scott Michael's book on Damsels is an excellent reference. I've seen auriventris in various LFS enough to know that,similar to P. alleni, they don't color up well if they're not happy. When they're happy, they're stunning. With my previous P. alleni I never could quite figure out what specifically was making them unhappy or happy. Sometimes the color was gorgeous; other times it was dull. I suspect because they are relatively mild-mannered, they need calm peacefull tankmates. HTH.