Had to do the same thing but had a different experience. It was hard to dive in and took some time but now I understand and appreciate the core concepts. There are many abstraction layers ("[...] schemes") and IMO that is a good thing. When you customize workflows etc. you can do that without leaving supported areas. Creating and changing a workflow is very easy. Plus, JIRA has a good pricing.
With ~350 employees and many mixed teams using only Trello would be chaos. In key areas we need fixed workflows (-> JIRA).
Right now we are planning to add Wekan (FOSS trello clone) to our toolchain for workflows which are more dynamic (less "C follows B follow A" + smaller teams - e.g. innovation and some planning).
I think buying Trello was great move for Atlassian. No way could Jira compete with them in the long run. And now they are even safe(r) from new Trello-like competitors. Brilliant move for Atlassian. Too bad for us users... :(