Anyone use both Freepbx and Grandstream's UCM's?

I’m weighing between just rolling my Freepbx or buying a Grandstream UCM. Anyone have experience with both? The GS looks neat, but I’m worried that they’ve only been in the PBX game less than two years that their firmware and featureset, not to mention their reliability, may not compare to more mature asterisk-based systems like freepbx. The hardware looks tempting, but if the software is junk, its just not worth considering.

The GUI on the Grandstream device is the AsteriskGUI that Digium abandoned years ago.