There are a couple of great resources that have been produced for us at European seminars over the last few years that allow you to compare various surround microphone arrays in blind listening tests.
This one contains ambience recordings:
http://www.hauptmikrofon.de/index.php?option=com_content&view=article&id=78&Itemid=87
This one contains orchestral recordings:
http://www.hauptmikrofon.de/index.php?option=com_content&view=article&id=68&Itemid=58