Yes, we have. I admit that I didn't make it visible on the site itself. But the system checks every single user every 5 seconds. We have two metrics: net value

Yes, we have. I admit that I didn't make it visible on the site itself. But the system checks every single user every 5 seconds. We have two metrics: net value and minimum net value. When NV < MNV, all positions are immediately liquidated. When NV < 2MNV, a warning is visible on trading panel. (Future feature: margin call email) These metrics are completely transparent, showing in different colors to represent health status. Once you give it a try you will know.