Since alerting the search engines is all you are doing, there really isn't any way for you to get a higher page rank just because the search engine knows that you are updating content on the blog. It might help you move up the search results a little but it's not going to bring that much closer to that top page rank as a website. 

Again, you are alerting the blog directories and search engines that you have updated your content not to give you favor. Increasing traffic is up to you and your marketing methods, not the pinging sites. Just alerting the search engines isn't enough to get your site some traffic. The search engines still have to properly place your content in the right search results based on keywords, page rank and other factors that the algorithms go by.