I can confirm that stealth gains stop, rock solid, at 84 without armor.
Then you can throw on whatever armor you want - but use 16 AR - and you will continue to gain - but you will gain S L O W L Y.
I macro'd last night for 8 hours, and went from 84 to 90.3.
Guide: Stealth
Re: Guide: Stealth
I stopped gaining at 88 with no armor. Threw on a couple pieces, maybe 11 AR and I'm at 90.x.