Scanning ssl vpn traffic

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Hi, I have a Juniper ssl vpn solution and have been tasked with 
providing a ips/virus scanning solution that scans traffic coming in 
from our users and 3rd parties that have been given access. I expect no 
more than 100 concurrent users within a financial environment that needs 
to be PCI compliant. I have been recommended Fortinet, but the 
appliances have quite small file size limits (below) so the size of the 
box versus our number of users doesn't add up.

Juniper also have a IDP range which may work well seeing as we have 
juniper ssl vpn gateways. Can anybody recommend either of these options 
or something better for good reasons? I'm not in a position to 
pyhsically evaluate any appliances myself unfortunately.

Many thanks!

FortiGate Model                        RAM      MAX size
50A, 60M, 60WiFi                     128MB     12MB
100A                                       256MB     25MB
200A, 300A, 400A, 1000A         512MB     50MB
500A, 800, 800F                         1GB      139MB
3600, 5000                                2GB      547MB