AFAIK, nothing has changed.
It's still a matter of luck.
IR still exists but you won't notice it 99,9% of the time during real life use. Actually plenty of people have an iPad with IR since months/year but never noticed it. For some it's a non issue: they have to use the special test to see it.
Yellowing still exists. Far more annoying than IR as you always see it.
Narrow gamut is by design. rMini has a narrower gamut than the bigger iPads.
rMini is a great device. Does not look for a perfect screen, just use it. 😎