If you consider "latest firmware update" September 2019...I'm surprised how infrequently Shimano updates their firmware. It sure isn't because they "got it right the first time"...
Three big issues remain for all of the Shimano eMTB drive systems, including the E8000 (which oddly enough did not get a firmware update to support the new larger capacity batteries) that can EASILY be addressed with software/app updates:
1) Requirement to have a dealer make changes to wheel circumference - I run different sizes wheels and tires throughout the year (my bike can run 29er and 27.5 plus, and I run different sized 27.5 plus tires seasonally)
2) Power tapers off steeply at 18.5 MPH, unlike most other eMTB drive systems. This is the achilles heel of the Shimano system, and again, easily addressed with a firmware/software update
3) Remaining battery indication is inconsistent between the battery (the five LEDs) and the display unit. They often do not match up. And the time lag between a low battery warning and shutdown is inconsistent and sometimes nearly non-existent.
Other quirks are inconsistencies in the data available via Bluetooth and/or ANT+ private from the various display units. Also the above mentioned lack of an update for the new batteries and the DU5000 display.
So in short, I do have plenty of complaints about Shimano and their software/firmware.
Thankfully, bricking the system isn't one of them....
Affects assist cutout point, not actual power/boost (I guess indirectly it sorta does). The difference can be substantial, actually. Range of 3-7% depending on tires. So a full MPH difference on average (5% difference).
I'm payin' for 20 MPH top end, I want 20, not 18.5 and certainly not 18. ;-) Where I really noticed this was in an eMTB race - those on non-Shimano systems had a 1-2 MPH advantage in the open sections and though I pedaled my ass off (HR was 156 average for the race!) I still was at a disadvantage.
Not super noticeable on everyday rides, but I did notice the cutoff on places like transfer stages or section of doubletrack/road.
Either way, it should not require a visit to the dealer and the cost/inconvenience. For that I reason, I bought a STunlocker license so I can set it myself. And every time I use it, I do worry about bricking my drive unit!