I would guess that you could expect a reduction in days off. Personally, I think a line where you are away from home 20 days is more fatiguing than a 15 day off line with a few 15 hour days.
I think rather than duty time, I'd like to see something preventing changes in duty periods. In other words, if you're duty period has been noon to midnight for four days followed by 1 day off then all the sudden you're expected to be ready for a 4am show! Screws up you’re sleep schedule just as bad as crossing 5 time zones!