There's a lot of confusion going on in that post...especially when it comes to "static IPs".
First...there are 2 sides to your network when it comes to routers that run in gateway mode. Static IPs can refer to either side...it depends on what you're talking about.
A static IP...or a block of static IPs, that you purchase from your ISP....are the "public" IP addresses that you obtain from your ISP. This is the IP address that you see when you go to "www.whatismyip.com". This is typically only done on business accounts from the ISP, and typically only used when you have things like a mail server running on your network (so your MX record points to it), or a VPN server, or remote access services like Terminal Server/TSGateway/RemoteWebWorkplace...stuff like that.
Now...static IPs on the inside...on your private network...such as when you have servers, network printers, network scanners/MFPs, stuff like that...Comcast (or whoever your ISP is) doesn't care about those...nor should they. Those are YOUR static devices which are on your private class C network behind the router (like 10.1.10.xxx behind the SMC or 192.168.0.xxx or 192.168.1.xxx behind your Nutgear or Stinksys router)....the ISP doesn't care about those, they have no need to. It's behind NAT..the basic hardware firewall of your network.
Now lots of us setup networks for our clients on Comcast business setups....typically with the SMC gateway. We want to use our own routers for various purposes, and not the SMC gateway. This is very easily done. The proper method is to take the sheet of paper that Comcast gave you, for your static IP block. Take the first usable static IP address...and assign that statically to the WAN port of your own router....and you'll see the default gateway for that IP is 1x number higher or lower...enter that for the gateway, enter your own DNS or Comcasts DNS...and uplink your own routers WAN port to one of the LAN ports of the SMC gateway. You can leave DHCP enabled on the SMC...your router is assigned with a static external interface, and your entire network will plug in BEHIND your own router. So DHCP from the SMC will not impact your own network. What you want to do is log into the SMCs web admin, firewall section, and put a check in the box for "disable firewall for true static IP subnet". Now your own router is not double NAT'd. Your entire network is behind it....192.168.0.xxx, there's just 1 gateway..and your own routers WAN interface is on the proper static public IP address from Comcast.
And yes the Netgear ProSafe routers will typically be a bottleneck on todays faster Docsis 3 networks....even older Docsis 2 networks of higher speeds. The ProSafes are not very fast.