I had used Free version for some time.
What sealed the Pro Version deal for me was the recent updated of adding menu items with URL's that display in iFrame!!!
This takes out all the work and relieves me of the work I had searched for trying to create a plugin to display a special menu item with iFrame content for my clients. Now I just add the menu, punch in my URL and select iFrame, and BOOM!
The ToolBar add-on for the Business edition is just great because I have WPMU Ultimate Branding plugin to assist with this but it's not as simple and it's an extra functionality I can get rid of now because I have this menu editing in one place with roles and capability features.
This is definitely one of my favorite and most used backend plugins!