Inbound Traffic on Gateway IP
So I just got Comcast Business with 5 Statics. After some (lengthy) experimentation, I finally got my static IPs sorted out by assigning each of the 5 statics as a separate IP on the IPv4 interface of the NIC for my Windows Server box (also ordered a multi-port NIC) and then using True Static IP Port Mgmt. on the gateway to allow only the desired inbound ports (80/443 for now).
Since I have (for example) x.x.x.15 – x.x.x.19 as my 5 statics, and x.x.x.20 as the gateway, doesn't that technically make for 6 static IP's, since the gateway IP (I assume) doesn't change, and since it is possible to map inbound traffic for the gateway IP using "regular" Port Forwarding?
My real question is this: Are there any business / practical / security / ToS-related reasons *not* to accept any inbound traffic on the gateway IP itself? (E.g., reduced throughput, safety concerns due to handling or increased likelihood of DDoS, not allowed by Comcast ToS, etc.)
Reason for asking is that I planned to use the 5 statics to divvy up amongst some small sites and web apps I'm serving, and had planned to use the gateway IP to accept connections for a VPN-passthrough down to a router on which my home network is based (subnet of which is thus isolated from the public server; poor man's firewall).
But, it occurred to me that since Comcast advertises it as "5" statics, rather than six, maybe there's a good reason not to accept inbound traffic on the gateway IP. Thoughts?