I believe the new firmware started being rolled out a few weeks ago in stages, not just a broad rollout. I don't exactly know what it's called now, but when you say open NAT, I'm guessing that's what it is. It used to be there were 1024 sessions, which seemed to be a problem with things like torrents. If the program was setup wrong, the torrents would saturate the connection. So people would call in, they'd send a tech, and then the tech has to explain to them that the service is fine, it's their equipment causing the problem.
But I'm thinking this was a huge issue. But what I'd like to know is how open NAT is any better if a connection can still be saturated? I'm not an expert, I just have 9 years of hands-on experience installing and repairing it.
There are also other options in the router, like guest wifi, if that interests you.
Authorized Service Provider (Contractor) for MTS Allstream. Any views expressed are my own.