Mambo was once top opensource CMS, but at some point due to bad business decisions and greediness, key developers quit and found Joomla.
It looks like things are going on here pretty much the same. I hope Xen succeed and try to pay attention to what customers want, also after success. I am to buy first license (money which would go to vB 4 if it would be cool software), but waiting for some goodies (prefixes for instance) first. In the mean time, I like how things are developing.