What a coincidence reading about this plugin! I'm the author of Broadcast, a multisite content sharing plugin that specializes in broadcasting content between sites on a network for... quite a few years now.

During that time I've encountered a whole bunch of Wordpress limitations that have had to be worked around: images, user roles, post status, links to other posts that have to be translated on each child site, PHP timeouts, etc.

Most of the upcoming features (WooCommerce products including variations, bbPress, several calendar plugins) Broadcast already supports. The PublishPress people are going to have a ball figuring out how multisite unfriendly some plugins are written.