I've tried a lot of newsgroup readers, and the best solution that I have is still newsbin pro running on parallels.
I have yet to come across a newsgroup reader for mac that will auto-monitor a folder for NZB files. I get great speed with Newsbin Pro too.
Also, if anyone knows of something that's similar to AutoUnpack (windows only), which automatically unpacks .rar files, repairs them if needed, and deletes them. It also monitors a specific folder, so all you have to do is click "start" and it pretty much does everything automatically. UnrarX does the job, but everything is manual. You have to drag the .rar files to the program, and you have to delete the parts manually later.
I pretty much just need Parallels for these 2 programs, it'd be nice to have everything running on mac natively. I could save some resources.