Never knew any different to Deere balers always thought they were the bees knees until the 854 turned up here hideous thing couldn't do a roll of net without chucking at least half a dozen loose ones, plus u could never get plenty weight in them , you live and learn and end up with a vicon RV...
I agree with your comments regarding seeing the pickup hitch even at full extension it's impossible too see on a T4.
It's a similar issue in other brands too.
There were some of the earlier ones that had a manufacturing fault with a circlip in the gear box that caused issues , there have been r series Deere's with similar issues too.
Clearly see in the mirror yes, you can't see the hitch on a t4 when trying to hitch up even at full extension. Easiest way is to use the top link to line up n then that horrible mirror like you say