@Gatorgrad OK, I think I've found some info that can be useful. Caveat I'm a serious amateur security fan, and much of what I've learned is from Steve and Leo and his fans. There are many people more knowledgeable than me. But, I try to make it accessible to average people through things I write. So, here's my opinion.
@Steve or others may also wish to comment. Bear in mind that we're talking about IPV4. I don't know about IPV6. Bear in mind also that I'm discussing home networks, not commercial ones.
I did a google search of dmz site:grc.com, which you can do since Steve publishes podcast transcripts. I got a couple of hits. These tell about using DMZ conventionally. Search for dmz within the web page.
SN EP 3, 2005
NAT Router and Security Solutions
SN EP 393, 2013 - Steve talks about your question. But, this content is a bit old.
Help Screen for DMZ in my DD-WRT router.
"Demilitarized Zone (DMZ)
The DMZ (DeMilitarized Zone) hosting feature allows one local user to be exposed to the Internet for use of a special-purpose service such as Internet gaming or videoconferencing. DMZ hosting forwards all the ports at the same time to one PC. The Port Forwarding feature is more secure because it only opens the ports you want to have opened, while DMZ hosting opens all the ports of one computer, exposing the computer so the Internet can see it.
Note
Any PC whose port is being forwarded must should have a new static IP address assigned to it because its IP address may change when using the DHCP function.
DMZ Host IP Address
To expose one PC to the Internet, select Enable and enter the computer's IP address in the DMZ Host IP Address field.
To disable the DMZ, keep the default setting, Disable."
When and How to Set Up DMZ
routerguide.net
This quote is interesting:
"Thus, when you are setting up a “home” DMZ or DMZ host, you have to be really careful. In fact, you generally should not use the home router’s DMZ function at all if you can avoid it."
They point out that, in the conventional usage, if one PC is getting all the unsolicited traffic, and if it is compromised, it can compromise your whole network.
With the exception of SN 393, all these are talking about conventional DMZ usage.
I googled dmz to nowhere and dmz to unused address and didn't get much.
Assuming that the router is working properly and bug free, I THINK DMZ to nowhere might be pretty safe.
But, personally, it makes me nervous for a few reasons. First, normally, the firewall blocks out all unsolicited packets. But, with DMZ, ALL that traffic coming to your public IP is getting inside your network, even if bound for a nowhere IP. That just sounds like a bad idea to me. Second, there might be a way that it could get to other computers, maybe with broadcast port numbers, etc. I don't know. Third, if you needed the DMZ for a game or something (still not recommended), you'd have to change it then change it back. This leads to possible mistakes. Fourth, you have to be REALLY sure the IP address will never be assigned by DHCP to anything on your network. If something ever gets that address, it's now outside the firewall effectively, and in danger.
If you want to shut down response to a certain port or range of ports, it's better to port forward just that port or range of ports to a nowhere IP. You can do that and still forward other ports to somewhere, if needed.
Steve mentions this process in this page.
Port Authority Database for 113
I'm not a gamer. And I don't run servers in my house. So, maybe I have a biased and simplistic point of view. But, my philosophy is no holes in the firewall, EVER.
Long answer to a short question. But, in my opinion, I'd still say avoid DMZ unless you have a pressing need for it.
Others are free to jump in here too.
Hope it helps.
Ron