do you actually keep information on your network that anyone would want?
people talk about 'security risks' all the time, but honestly, unless you have something people really want, then what's the problem?
me personally? No not really just some client contact information and invoices for my side business, but besides that nothing. However, DMZ puts a machine outside your router which opens you up for all kinds of attacks. The whole point of NAT is it does not allow remote hosts to connect, so it is considered a security feature.
Lets say your DMZ box gets spyware/malware/viruses from another node on your ISPs network. Since how cable works, is everyone in a certain area is on the same node. Meaning if your neighbor gets a propagating virus on their system it could connect to your DMZ box, and thus spread itself to your internal network possibly.
I do not run any software firewalls, no anti virus and no anti spwyare because I just secure my network, don't download stupid crap, and use web based email. I also keep stuff backed up. I have been completely 100% virus free since 2000 when i got my first router with NAT.
Sure DMZ makes it easy for some things, but I know how to configure everything in my router so I don't need to use DMZ, so I never have to deal with the security risk. Its my preference, like running DMZ is your preference.