load balancing XG webproxy

I have to point out: You still want to stick to the old proxy? There is a reason, its called "Legacy Web proxy". SFOS is moving towards TLS/SSL Decryption via DPI Engine, and this engine is a "Transparent stream based engine" and not a "proxy (Call it via 8080/3128)". 

So the question would be, if you want to migrate and utilize this new technology anyway or stick to this old concept. 

In this instance, the devices are not a part of the default route for traffic, so there is no option to migrate away from the legacy webproxy. This is due to the way our network is configured. Re-architecting the network isn't an option.

As SFOS does not host the WPAD i cannot see, what the Firewall has actually to do with this request. Isnt this a job of the F5 to load balance? SFOS / UTM seems to be just the N proxies in this setup, and F5 is loadbalancing the traffic. 

Correct, I just wasn't sure if I was missing something with the XG / wpad that is all. Or if any other users had figured out a slick method of load balancing XG's being utilised as a proxy.