It is tremendously efficient and works very well over low bandwidth links which, even in 2015, one encounters from time to time.
The key aspect of this setup, however, is that no mail is stored locally at all - I connect to a co-located server (you could also use a VPS) over SSH and run alpine on the remote system. Two very nice things are accomplished here:
1. No email on my local system - nothing to lose, nothing to be confiscated or intercepted or lost.
2. Many, many emails do not traverse the Internet at all. If I send email to an rsync.net coworker, that email is nothing but a local copy operation - it never travels across any network.
So I am excited and interested to see a console email client like this, especially since (al)pine is not really maintained and has fallen behind a bit in usability ... but I question the use-case of running it locally.