If I visit any good website and like to receive updates I prefer signing up for RSS updates via email instead of twitter. Why? Because many sites or individuals do not just tweet about updates of their own site but they tweet useful and interesting links from all over the web. What do you prefer?
RSS is the most convenient way. If you signup for a RSS for particular website, that website is responsible for the data they share. But when it come to twitter, Well any body can post anything... Its just a keyword filtering system of various user inputs.