Should I star using Userlist From Day One

Hi Guys, I'm looking for your valuable feedback here. I'm going to launch the my website and blog to build my beta user list. I will have only 2 objectives, to build an email list for earlier beta users and get more subscribers for the blog and other content resources. Shall I use MailChimp for both audiences or Shall I use Userlist (for beta access user) and Mailchimp (content subscribers) Cheers!