For music,I don't know whether it is going to be an upgrade or downgrade as I haven't heard the Heir 4ai. But I'm glad you asked about gaming, because just yesterday I was playing Need For Speed and I don't usually use my dt880's with gaming on my ps3 mainly because the cable is not long enough (I sit really far from the tv screen) and I already have a gaming headset with a mic that I can move around more easily than the dt880's. Anyway, as soon as I put them on, I noticed how clearer everything was (than my gaming headset). I could hear the raindrops making contact with the ground, and the storm right above my head. It really felt like real life, positioning was better and everything was just more lifelike and more immersive.
That being said, the dt880's are not really the best of the best in terms of gaming, look into the DT990 if you want that. They're very similar to the dt880's but with more bass and treble and slightly less midrange,, and of course a bigger soundstage with better imaging.
Thanks for the information. I think I read somewhere else that these were good for gaming or maybe it was one of the other beyerdynamic headphones I can't remember. But I think it would be great to hear every little detail like that. I thought about getting the DT990 and was looking at some review of them on youtube and found out that there is a lot of sound that bleeds out of them. There completely open and pretty much everything your listening to can be heard by someone standing next to you. I didn't want that to be a problem if someone was watching TV right next to me or something so I think it might be better for me to get the DT880 as its semi-closed so not nearly as much sound comes out. But the bigger soundstage and better imaging might persuade me to get them anyways I'll have to think about it some more.