Sizing question:How much workload can one firewall take?

[OTSTech]

Hello,

My company switched to a Fortigate 201e from cisco products a couple years ago as their main firewall.  It has worked great for the surfing/email needs of our 150-200 users.  We have been maintaining an ASA to do only AnyConnect since then.  We really like the Fortigate world better and have started testing the SSL-VPN with the Forticlient to replace the anyconnect.  We would eventually have 150 users but the most we get at one time is about 60.  We are also thinking of trying out the Fortigate Site to Site IPSec tunnel to connect in a five person office.  Right now on the dashboard, the fortigate never goes above 10% on the CPU.  Is it too much to expect of this firewall to do all those jobs?  I could buy another one, assign it another public IP from our range and funnel VPN and Site to Site through there if that would be better.  If I need more info to get a recommendation please let me know.

Thanks for your help!