I had been using Alessandro MS2i's for over three years before I had a very similar conclusion to you. I have recently listened to Oppo PM-2, HE400i, HD650, DT990, AT2000x, T5p, T90, DT1770. A few months ago I demo'd quite a lot of headphones and ended up buying the Beyerdynamic T90's. I think the general sound signature is similar-ish to the Alessandro/Grado sound so it was not difficult to adjust, but it is less harsh and more accurate. The comfort and build quality is absolutely fantastic. The soundstage is also more open. The bass extends very deep and is not boomy. I listen to all kinds of music.
I almost ended up with the HE400i's, they are very good but I thought slightly less fun. It is likely because of the sound I was used to. I also seriously considered the HD650's, but I thought the highs sounded very veiled, also likely due to the sound signature I was used to.
Hope that helps.
