Is this too much for a Balance One?

We have been having some issues with VOIP packet loss during busy periods. We have QoS set up and are working to eliminate possible issues before upgrading our networking hardware. I am not quite sure what the 60 User recommended limit is on this device. Overall we have a pretty atypical network environment with many devices per user including VOIP clients, servers, industrial machines, etc. At any one time we have about 20-30 people on the network, but the total number of IP addresses in our LAN is between 100 and 200. I had a Balance One at my previous company where we had a very similar number of people (35 users) but the number of internal IPs was only around 75 due to a smaller amount of IP devices and we never had any issues. Both locations use similar 500/500 fiber connections. How is the maximum number of users calculated? Is it based on the number of simultaneous IP Clients, Active Sessions or another measure? Lastly, besides the 100 to 200 active IP clients, I am attaching a screenshot of active sessions. Can someone verify if this load is acceptable for a Balance One (especially with respect to VOIP traffic) please? If this is too much, then what are our upgrade options? Thank you!

What firmware version is this on? Other than QoS, are there any other application or load balancing policies in play? VLANs?

At peak times when the issue is present, you may be able to login and take a look at CPU and real-time Bandwidth utilization. If the CPU is maxed for long periods of time when experiencing issues - and in the green when not - that may be an indicator it is time to upgrade. If the network or bandwidth utilization is extremely high at peak times, that may be a cause.

Any switches (older,10/100) that may be causing a bottleneck?