Here is the current implementation:
Pub 80:
Allows over capping of DCI.
Max Defense Chance Increase is 45.
HLD is -25 to current DCI.
45dci - lose 25dci, now have: 20dci
50dci - lose 25dci, now have: 25dci
55dci - lose 25dci, now have: 30dci
60dci - lose 25dci, now have: 35dci
65dci - lose 25dci, now have: 40dci
70dci - lose 25dci, now have: 45dci (Hld proof)
Pub 81:
Allows over capping of DCI.
Max Defense Chance Increase is 45 by default but can be increased to 95 using Armor Refinement.
HLD now scales -55% of current Max Defense Chance Increase to current DCI.
max dci 45 & 45dci - lose 25dci, now have: 20dci
max dci 45 & 50dci - lose 25dci, now have: 25dci
max dci 45 & 55dci - lose 25dci, now have: 30dci
max dci 45 & 60dci - lose 25dci, now have: 35dci
max dci 45 & 65dci - lose 25dci, now have: 40dci
max dci 45 & 70dci - lose 25dci, now have: 45dci (Hld proof)
max dci 55 & 45dci - lose 30dci, now have: 15dci
max dci 55 & 50dci - lose 30dci, now have: 20dci
max dci 55 & 55dci - lose 30dci, now have: 25dci
max dci 55 & 60dci - lose 30dci, now have: 30dci
max dci 55 & 65dci - lose 30dci, now have: 35dci
max dci 55 & 85dci - lose 30dci, now have: 55dci (Hld proof)
.....
Hope this answers your question.