I've got very limited Forum time right now, but I'll do my best to answer questions.
I think the new price for CMI Alveary is $199/yr per family going forward. I think they pegged their prices on Classical Conversations and then realized that was the wrong peg. The pilot group spoke loud and clear and the Alveary leaders listened. :-)
The pilot group was required to go to a conference because CMI only wanted piloters who were sold on the CM philosophy. For years not giving feedback that is no longer an issue. I went to a CMI conference when I was really burnt out and needed a conference that was about teaching, not family life. I found it to be a breath of fresh air and really was built up by the talks by Carroll Smith about dualism in education as well as current research on narration, and by the talks by Jen Spencer. Both are amazing researchers (Carroll Smith was an education professor and supervised Jen Spencer's education PhD) and do a great job talking about how current research ties in with Mason's ideas. So, when Carroll Smith and Jen Spencer announced this curriculum they were developing, I was sold.
I had spent the last year with Ambleside but was frustrated with the racial language in the books (though Alveary tries to be more modern, they still have issues with some older books - argh) and the fact that I felt like we were just pushing through book after book after book and narration after narration after narration. I didn't like AO science and AO science books (I think the Alveary's are much much much better). I loved hearing about things being learned about notebooks and timelines etc from the Parents' Review and longed for someone to hold my hand in implementing them. Alveary has done a great job with that.
Our days are so different than with Ambleside. I freely admit that I didn't do AO right - I didn't have the time to figure out all the things I needed to figure out to do it right, and there were too many books for us to do it right. With Alveary, we do so many different things every day and I have someone guiding me through what that should look like. We literally sing, dance, do crafts, do daily nature study (yep - that's what Nicole found when she actually read up on what CM schools did), read, write, do foreign language, etc etc etc. We have gotten so much done by doing a bit every single day.
It is definitely rigorous, and I'm pretty critical when it comes to judging that! I did adjust each kid as needed, but the Alveary allows that because you have access to all levels (or at least we did this year, and I think that is the plan going forward). It is designed to follow Mason's plan of fairly short lessons, though, so if you define rigorous as 90 minute lessons, you probably won't like it.
I don't think you would want to keep a 12 and 8 year old together completely, but each could read their own history spine on their own about the same general time period and then be together for the same family read aloud. We're doing that with one in the car right now.
The Alveary has had a lot of flexibility this year; if enough people disliked a selection, then the Alveary made a change. But people who found that a selection worked for them weren't forced to change.
I do find it complete, though I have my kids do more math than they recommend because we are a math family. I also bumped up my kids one level in science because my kids have breathed science since they were little.
Gotta go, more later.