AMC is not open source.
http://www.ares-shop.deBroadway is based on the AROS nightlies, while it is a mix of many builds.
Because sometime some parts get broken, so sometimes it is better to stick on an older file.
Broadway is the same + preinstalled apps (not all of them are opensource).
The difference to a nightly is that Broadway is preconfigured to run on AresOne. So sound and ethernet works out of the box, while on an other machines you will need to chose another device driver.
But don't worry. People like you piss me off too. That's the reason why next Broadway will be last Broadway release. For you it is money, for me it is time.
I think 2 distributions are really enough.