ThreeWP Broadcast is a great plugin. We use it to help manage K-12 School websites. It allows us to post important information to over 32 school websites at once.
We have found that when trying to publish to 30 blogs at once, you need to increase memory and the timeout time for PHP. After adjusting those parameters in the php.ini file we were 100% successful in publishing. With every post our blogs also send out emails to subscribers, so the publishing time is increased as the server sends out the emails before publishing.
There seems to be some initial compatibility issues with WordPress 3.5 but we are hopeful that these can be addressed.