I read that post about the Seafoam. I was somewhat tempted, but I also felt like I really wanted to get it well and truly fixed! (I think I even found your post where you'd mentioned the leaking again? Not sure.) Anyway, I can understand why the Seafoam works, for some people, if the problem is a leak somewhere.
I don't want to be TOO optimistic, but if your transmission is shifting fine while driving, I would think that a total rebuild is overkill. Does the "limp mode" symbol ever come on? That's definitely a Bad Thing, but if it doesn't, it sounds like your transmission is generally okay. It would be a real bummer to spend $2500 or more on a rebuild when it's really a leak that can be fixed for a few hundred dollars. The main problem is that, no matter what the issue is, you have to open up and then re-seal the thing. I've told the guys at the shop I go to not to worry about opening it up until I've either found a suggestion or have given up on finding a suggestion. But if you don't have the light coming on, if the car drives fine, and if the fluid that does leak out is not ugly, I think I'd want several opinions before I let someone rebuild my transmission.