Definately YES get Portnoy back! I loved the more metal direction the band where going in as i loved metal before i loved DT. Time is a healer. Mangini was fantastic when I saw DT live with him, but although i started to appreciate ADToE a bit more, i just prefer the style and the sound of Portnoy.
I may be wrong, but im under the impression DT wanted Jordan before they hired Derek, but later fired Derek and got Jordan, so I have no doubt that if the situation arose they would release Mangini and get Portnoy back if they wanted. Once the honeymoon period is over they may start to miss Mike.
Lets see how the next album is... Personally i wouldnt want another I&W or Awake, i wouldnt want a similar sound to ADToE, i would like a slightly heavier album, but ultimately I hope they reinvent themselves again, if they dont change their sound and keep using all the same guitar tones and Jordan keeps using 10 different patches per song, i think it could get stale quite quickly and I actually think DT should have had a break... Maybe for just 2 or 3 years.
Mangini is great, Mangini could be far superior to Portnoy, but for me MM isnt Portnoy. The DT I love is MP, JP, JM, JLB and any of the keyboardists. The DT album without MP doesnt sound like DT to me. I try not to get caught up in squabbling musicians and the soap opera of it all - i dont care, i just care about the music so im not gonna hold any of his outbursts against him and his drumming. Portnoy is the man!