Are MailChimp & eNewsletter WPMU plugin redundant?

I have eNewsletters installed. My concern with using it is 1. I've not been able to set up the SMPT correctly, 2. If I do get it figured out, it will draw on server resources AND possibility many of the emails will end up in people's bulkmailbox.

I also have a mailchip account. Is it redundant to be using both the eNewsletter plugin and the mailchimp account?

I'd rather go just with mailchimp if possible. But how does this impact people who want to sign up as "subscribers" role so they can cooment on posts?