That said, I'd suggest a higher plan, preferably with mailing list integration, to allow you to participate in group promos. They've been working very well lately. I tend to get an average of 5 subscribers a day from the promos.
I agree with that - I use the secure mail option to send out ARCs, and the mailing list integration is great because you can put people from different landing pages for the same book into different groups.
E.g. when I advertise on Facebook, I use a signup page, and in Mailerlite I can see how many clicks on the ad converted into new ML subscribers.
Can't remember the name of the plan I went for, but it was Midlist plus something.
Okay, just looked it up: Mid-List Author with Integrations Annual