I have been using MultiRack over AVB since I got my StudioLive Series III and it works better than was described in kevinmorehouse's previous answer.
In Universal Control I route my channel via AVB using the 'Network' selection. I make sure that the channel's send is set to 'Analog' source. Then in MultiRack configure your rack to use the same input and output channels (example: ch 1 in, ch 1 out). Back in Universal Control you can select whether your Presonus signal processing will happen before or after your Multirack processing by configuring the 'pre' or 'post' send options. Using this configuration, you can use a single mixer channel in Universal Control, while passing your signal through MultiRack for plugin processing.
This has worked for me since day one and I've been using it in live settings for several months.