@jan:
My only apprehension are the servers that are publicly accessible, currently they are configured via 1:1 NAT, will WAN2 affect this? With regards to failover, if WAN1 goes down, what will happen to the publicly accessible servers? Will they still be accessible via WAN2? If not, what should be done in order for it to be accessible via WAN2?
TIA
You could configure an additional 1:1 NAT on WAN2 for the servers, which would make them accessible from either WAN, however the client needs to be 'smart' and figure out to switch to the other address. Doing failover for incoming WAN traffic is basically impossible with different ISPs on each WAN link unless you obtain an ASN and ARIN IP allocation, and obtain BGP-aware connections from your ISPs. This is a pretty high-end setup not available on most non-leased-line connections that requires quite a bit of expertise to do properly (and something more powerful than pfSense (Cisco or Vyatta etc.). If you really need this, setting up a cluster at a reliable datacentre to act as a smart failover proxy for the traffic makes sense, but if you're going to that expense it often makes more sense to just run the services on the hosted machine.
WAN2 won't affect your existing 1:1 NAT configuration though, so if you're fine with the status quo w.r.t. reliability, you shouldn't have to make any changes. pfSense is state-aware, so only new outgoing connections will follow the policy routing rules; return traffic on incoming connections will go out the interface the connection came in on.