I have been looking at the PageLines platform Pro for a while now. Like premiumwp said it seemed like an advanced framework. But there is however part that, oh well, sucks big times.
When they started promoting their product they said that Platform is great for developers who know how to code and just want to jump in at adding more advanced features. They are selling Developer pro license for $250 plus $20 bucks a month.
Now, as developer, it does not seem that you can develop anything. You can extend css or make child theme but you can not dive into the framework. Well, that just suck.
So at the end, you will end up paying for some product that will eventually screw you at some point. Their politics really made me mad. Platform looks nice, but there is just not enough what you can do with it.
Specially NOT for that price since there is no way for you to sell your theme work.