Realistically, do I NEED pro-active mode?

If i am sitting behind two hardware firewalls, and don’t install programs willy-nilly, do I really need anything more than the default settings?

I know more is always better, but realistically, what really is the risk to get an infection compared to using the proactive mode?

If you are behind a NAT router you’re good to go. Myself, I’m not thus the need for a firewall with HIPS.
I have a laptop thus Comodo Firewall is a perfect choice, especially if I use a public wifi. Of course I have tweeked the settings to my preferences. 8)