Symantec Gateway Security vs Router

Currently, I have a router that have extremely tough security settings.
I'm wandering if is worth it to switch to a Symantec Gateway Security
1620. Ignore everything else except the Firewall component, is the
Symantec Gateway Security 1620 stronger than a regular router with SPI
and NAT?

The only real differences I see on the Firewall side is that the
Symantec unit also protects zero day attacks and that's about it.

Please advise.

Thanks.