I don't get it, why not use _any_ client with IMAP instead?
A lot of online commenters refuse to believe this but the standard Gmail interface is highly optimized to cope with bad network connections, hide latency, and recover from interruptions. If you have the code assets and initial state cached in your browser, it behaves very well under bad network conditions.
but I was on a flight, didn't have Gmail or Superhuman cached and could not get either to even load. I do suspect that if it were already loaded, Gmail probably would have functioned decently well.
still Gmail and Superhuman just seem...bloated. kinda cool to just have a simple, open source interface for the Gmail REST API.