The pure nature of torrents is a 2 way thing, you are uploading at the same time as you are downloading thats how torrents work, as far as I can remember.
Most of the court cases you hear about are people using torrents or p2p. It's very rare that you find anyone getting done for downloading from newsgroups.
Peerguardian is fine, but you cant hide your IP from your ISP, and now they are legally bound to provide this when asked to do so. (if they comply and some say they wont).
How can you veryfy any of the IP addresses that you are connected to, they could be anything from a hacker to law enforcement.
It's easy to see what you are downloading from torrents as everything is a binary file.
The newsgroups are totally different, for a start there are no binary files on any newsgroup server anywhere. Sounds daft I know cos you can download films and music and stuff.
To upload something to a newsgroup you take your binary file the run the upload program, this will turn it into text, called UUencoding, it's split into 100's of messages that are stored on the newsgroup server, when you download using any program except outlook express, the program automatically joins and UUdecodes the messages which end up as binary files on your pc. This is just a basic encoding, but would still need some effort and time for enforcement to findout whats being downloaded, they cant just go off filenames to make a case.
Add into the mix SSL encryption which encrypts data on the newsserver before sending it to you and your program un-encrypts it once downloaded. It makes the newsgroups one of the safest ways to download. And you are never connected anything but a server. Some of which are purposly situated in countries with no copyrite laws, like Isreal, so they never get raided.
NZB site are different, they dont really have anything to do with newsgroups in the same way the Pirate bay works. NZB's were invented because it's easier than trolling through 1000's of headers to find what you want. But there is far much more stuff available to download than NZB's are created for it. The newsgroups (usenet) pre-date the web (not the net) by around 10 years, and NZB's have only become popular in the last 8 or 9 years.
If you want even safer then you can use IRC, but thats a different story, and where the big boys hang out (the rippers, crackers, hackers, packers, and distribution groups). Effnet is the place to be, apparently.
As for download limits, Virgin have never complained about me downloading 600-800 gig per month for the last 6 years or so. I schedule my downloads for overnight so I never get bothered by their traffic shaping.
At the end of the day it's what ever works for you. Newsgroups help my sense of paranoia, I could'nt do torrents or p2p.
