I think it should be 12 for the rucksack, 24 for the emperium aura, but probably more. It doesn't make sense that the Black Emperium Aura should be so hard to get, and this event aura be that easy. Yes I know it will take a long time, but players should have to work for long term goals to increase participation every week in the event.
I like the best 2 out of 3 thing - kind of like console fighting games. And I disagree with not allowing people to be able to reflect/suicide a Champion's Asura. I see Champions in LMS, PVP Laddering, WOE, and GVG all the time - a smart Champion tests the other player first using melee to determine what asura to use. If the Champion is bad enough to go in with a full asura before seeing if the other player is using reflect gear, then it's the Champion's fault and he should get eliminated for his mistake. Also, the opposing player should get eliminated as well since it was their decision to go in and risk their position in the event to take out another player.
Going full reflect is a viable build and strategy and should be allowed.
I have a question - do you have to enter in with a proposed class, or can you just enter and then see who you're paired against, and then decide the class (before knowing what they choose). I feel like that could lead to better matchups - if you are a well versed PVPer, then you should be able to predict what class your opponent will play.