As I've been traversing Linkreferral and Entrecard, I've noticed that a lot of them have one or the other, but the really 'savvy' ones have both.
What is special about Linkreferral is that it allows a written review - read yours carefully and think about them. What are people saying that they like about your blog? What should you add/leave out?
Entrecard gets you the visitors, but you have to keep them if the monetising aspects of your blog are going to work. OK, you aren't going to keep the ec accumulators who use a bot to drop on 300 blogs a day. They don't have time to think about your content and they don't care.
If you are lucky, the folks that visit from Linkreferral AND have entrecard will drop on your widget because it's natural for them.
The really interested ones from entrecard - probably the ones who you've commented - will, if they like what they see, will review you on Linkreferral. Either way your ratings will go up, more of your posts will get seen and hopefully you will get more customers.
It's an organic viral thing - make the most of it.