I know that a lot of people like AS, some people REALLY like it and I'm a little concerned I'll get jumped on for saying this, but... I used AS from the start on my 30 gallon high tech tank, and I don't think I would ever use it again unless I was doing a small (10 gallons or so) high tech tank with very difficult plants. AS does grow plants well, but it was a real PITA for me to work with. Any time I disturb it even a little, I get a giant mud cloud. In the beginning, the cloudiness was so bad that I could do a full water change and still not be able to see the back of the tank. The cloud was brown and the ammonia was fine, I never had an ammonia spike with it, but I also started the tank with Bio-Spira so that could be why. It was just a big, ugly cloud of mud. It still gets nearly as bad, if I even move a few things around, there's a cloud. Forget trying to change the hardscape or move well rooted plants. You pull up anything and it looks like the mud version of some avalanche footage. It's ridiculous. This is why I say I'd consider it for a small tank - I can easily change out all the water if necessary. Some people have told me I must have got a bum batch, which is quite possible, but I've heard of the mud issue from enough other people to think that if it is a manufacturing issue, it's not worth the risk versus the expense. It's not like you can tell it's going to be muddy until it's already in your tank and wet.
I was also never able to get AS to hold a slope or anything. I made the mistake of being duped into buying "powersand" to go underneath it, which afterwards I realized was totally unnecessary, and the ugly powersand all ended up on the top of the AS anyway. Apparently it's lighter or something, because any time the substrate was disturbed at all, tons of powersand would come up. I could never get it to stay reburied, I had to resort to picking it out by hand because it was so ugly, and I eventually gave up on that because there was always more to come up. And once that powersand is on the surface, it grows algae like crazy, so then I had chunks of ugly, green powersand instead of ugly, biege powersand sitting on the top of my substrate. I could have done a clado foreground with the chunks of powersand if I wanted to. The moral of the story: if you DO go with AS, don't add powersand.
Also, in my experience, fert dosing was still necessary even in the beginning. I tried without ferts, and that did not work because my tank started to get different kinds of algae based on nutrient deficiencies in the water, and my plants started to show deficiencies. This stuff wasn't cured, it would just go from one problem to the next until I gave in and started dosing EI. Since then I've also tried PPS-Pro, and that works too, but whatever the case is it became clear to me that there needed to be some balanced nutrients in the water despite the fact that I had Amano's miracle substrate. The way I hear it, Eco Complete doesn't have much in the way of available nutrients, but it does absorb what's in the water. If I have to go to the trouble of dosing the water column every day anyway, why not go with a cheaper and easier to work with substrate that will absorb things anyway. I could be wrong about the technicalities of how it works, that's just my understanding from what I've read here. Whatever the case is, I've seen PLENTY of excellent looking tanks using Eco Complete, and I've seen Eco Complete tanks growing pretty much any kind of plant you can think of, I personally believe that's probably based more on lighting, CO2 and nutrients than the substrate itself, especially considering that most difficult plants are stem plants of some kind.
These are just my experiences, but I'd go with Eco. I'm doing an Eco cap on a MTS tank now. I know some people are asking why I'd do MTS if I had a problem with mud, but see, if I'm going to have a mud cloud I want it to be because I actually DO have mud in my tank. If I voluntarily put the mud there, I'm okay with it. :tongue: