to be honest i do not think anyone knows how the numbers currently work in regards to elusivity right now. mainly because the in game numbers seem to be really off in pvp right now. if some one knows I haven't seen it posted anywhere. i have heard that there are some powers that allow elusivity to stack but i forget where and how much.
tried logging in my widow to check attribute window, but it doesnt say anything about elusivity, nor does the powers window.
I think the problem is found: some of the sets that claim 30% elusivity actually get about 50%, and unlike the diminishing returns you get in most of pvp, elusivity gets massive increasing returns. 50% elusivity will turn 300% accuracy into 150% accuracy.
It's tough to judge the numbers when you're actually playing, because you play random people with random builds. I'm a numbers guy and this would explain a lot.
Edit: Energy Aura also seems to have enhanceable elusivity. In overload, you could get about 80% elusivity to all. A character with 300%! accuracy attacks AND to hit capped at about 30%, attacking the energy aura character self-buffed to about 50% def would have a:
(3*.2)*(.5+.3-.5)=18% chance to hit. That's pretty much the best chance anyone can get to hit this character, and this is not pff; the character can still attack.
I was looking at powers on city of data, and see widow's elusivity doesn't say ignores enhancements and buffs like most of them do. Does that mean that their 30% elusivity is actually 50%? If true, that just killed all my pvp desire right there and I take back my previous position that pvp was improved with i13.