sorry for such a long response...
Hi again Tom,
well, the 55 gallon is the tank I have these guys in. Of course I've switched things around since my tank spec post (I really need to get back there for updating) as to what's left in the 55 I speak of is 3 discus, not full size yet but growing fast, a few cories, and a lemon pleco, 2 bolivian rams...oh, and of course my male Angel. I've moved the puffers, the RTS, the common pleco, a few cories, 2 more rams, and the newest addition of 2 kribs into another 55 gallon. With this one, the only change I am considering is bringing the pleco to the LFS for a smaller type.
With the Angel/discus tank (my fav of the two) here are my details. I have a few (not many at all) small plants and java moss, along with 2 pieces of driftwood. The gravel is a natural color with substrate underneath for the plants (I forget the name, Lourite maybe(?)). I feed them tropical granules from Tetra, for large fish in the morning and Flakes at around 7-ish at night. They get bloodworm treats once a week. I've read the Discus need 2 feedings daily while growing. My Angel, without his fins is about 6 inches with fins, about 2.5 without. When I got the discus, I went by the size of the angel without the fins. I've had the discus for a little over 2 months or so, maybe 3. Two of them are slower at growing than the one is, the smaller ones being about 4 inches (with fins) and the bigger one being about an inch taller. I think they've probably grown an inch and a half each since I went and got them. I change the water once every 4 days at 25-30% religiously (I'm sure you've discovered the pristine water conditions needed by the discus, to not do so would be way too expensive of a risk for the discus).
My Angel is a brilliant silver with verticle stripes and the one I just lost was a marble. They have been know to spawn, though never in the company of the discus so I'm not sure of the aggression patterns for the discus during Angel spawning. The discus are from smallest to biggest, a Pigeon Blood, the next is a Cobalt, and the biggest is a Royal Blue. I must say that despite the wide diversity I have here, I do find a relaxing eye when it comes to peering in this tank. While each is so different from the next, it is this diversity that allows you to look throughout the entire tank and not just on one point. That may not be what one looks for in looking for a single spotlight in the tank, my idea was to bring the viewer to the entire tank without settling on just one thing. Each adds their own individual beauty, therefore beautifying the entire space. I don't believe one cuts out the beauty of any other, they just enhance things. I believe it's nice to be able to see diversity.
I haven't had a problem yet as far as aggression is concerned other than I have already mentioned so I would say go for it. I also read somewhere that the more wild the species of Angel you get, the more likely it is they will carry the disease that is fatal to the discus. I hope I've included what you needed here, but by all means let me know if you need more info.....I'll be glad to help.