That being said, how do you intend to be different from Trello?
My plan is to add functionality--initially realtime collaboration--and then comments, tasks, assigned users, point/time tracking, etc. but make all of the features opt-in and customizable.
I consider this the real minimum viable product. Just a list of items. Priority represented by position in a list. Status respresented by WHICH list. An unobtrusive backlog. An accessible archive. I want people to be able to use it at this level of simplicity a year from now.
The one (only?) thing about Trello that I don't love is the number of pop up screens, etc. I want ThetaBoard to be a single interface where you can do what you need from the one page. If that makes any sense.
This is not a suggestion just a comment/wish, I'd like to see some app like yours offer the ability to store/retrieve data from a web service that we can provide to you but written to your specification, not sure if something like that is possible, but it would be preferable to a packaged application my small team cannot afford. I haven't seen a SaaS app take this approach, but it is interesting to think how it might work. UI as a Service?