Hopefully, someone with more experience will come along, but I have had 7 Itungi acei since last August. I haven't kept other acei variants, but based on what I've read, the Itungi behave similarly. The coloration of the sub-doms varies from light to dark black with yellow fins, while the most dominant often displays blue on his face and sometimes hints on his body when he's really showing off. The dominant also has a little more white in his dorsal fin. I keep them with msobos, hongi, and white labs, and the acei are very attention grabbing. They're definitely one of my favorites, and I would highly recommend them.
My pictures tend to not do them justice, so here's a link to the person who I got my acei from:
http://www.cichlid-forum.com/phpBB/view ... f35c861038
If you've seen the ngara (white tails), these guys are very similar but with prettier yellow tails (I may be biased).