When using the console-cli we noticed the the system filter has not effect when fetching the 'current' status but had an effect when fetching the 'live' one. According to the online documentation and '-h' on the command line, the system filter only applies to status, yet it works for the other commands such as bounce and the live status, but not plain status.
The documentation should probably be updated to reflect the actual behavior (that the filter works for the commands, but not the 'static' model). If the model/static api gets updated to support the filter that's fine we me, since we could take advantage of that with the automation we built around the console.
Re: systemFilter not effective on 'current' model API
I have not looked at the code yet, but it seems that you should be able to apply the filter on /static as well. I will investigate further (note that my "electronic life" is currently in transit between Hawaii and Las Vegas and so it will take a bit longer to be able to do anything ;)