Yeah Litchi works fine for regular flying, but waypoint missions requires v1.4.0.10 firmware (07/09/15) or above so again, perhaps not a problem,
No Inspire 1 firmware updates for over a year now going by the DJI release notes.
Not looked in rooting, parameter hacks, NFZ removal, etc, yet - that’s next on my list 
@Gadgerman had a thread recently about downgrading as newer versions have limited the transmission power, a bit like FCC/CE on the MP from what I can make out. Thankfully mine has never been updated since the day it left the factory three years ago 
That said, downgrading seems to be straight forward but they put something in place in v1.9.1.30 that then only allows rolling back as far as v1.8.1.00 (if that makes sense).