@Shivservant thats really odd that you were having speed issues with Newshosting because they max me out all day long, I get 1.1MB/sec constant, I would check your routes to make sure there isnt a better port you should use before you switch
http://www.newshosting.com/support/util/traceroute/

As far as retention goes, using NZBs GN and Newshosting are the same, Giganews is just more expensive