I have heard some people mention something about a 511 put perhaps they were mistaken for a 510. Maybe they wanted to name it the 510 at first and then make it 511 later on as an enhancement of the 510.
So are the rev. 013 301's going to be considered a 311 while the rev. 010 301's are going to be considered a 301 still?
most of the features of the 311, except the built in card, are being rolled to the 301 with software. the enhanced guide, hide locked channels and updated error message windows. there really is no reason for it right now.
The smart card is built in with the 311 and the 301 still has one you can access in the front. That is the only thing I can see different. The built in smart card is suppossed to be a way to beat hackers.