In your experience, is a TM backup to a NAS as reliable as a TM backup to a Time Capsule? I ask this because Apple officially does not support TM backup to a HDD connected to an Airport Extreme (http://support.apple.com/kb/HT1427?viewlocale=en_US). Although some have success with this method, others don't so I skip this option. A NAS however, is not excluded from Apple's same support page. So I wonder how reliable that option is (as an alternative to a Time Capsule).