If you've written a good article, why post it to Ezine - or any other article site - rather than your own website? All you're doing is giving the article site the traffic you could have had on your own site.
As far as articles already published go, I wouldn't bother republishing them on your own site. Search engines will already have indexed them under Ezine, so the chances are that if your article appears in search results, it will be with the Ezine link and not with your site. Concentrate on high-quality, unique content for your site.