My first test results are in. The bottom part of the light dunked in liquid nitrogen!!!! I figure thermal shock would be the best way to coax the rivet off the body. First warm the light up real good with heat gun. Twist head on/off ten times. Re-heat, dunk bottom half into LN2 for 30 seconds. Take out, hold onto it with a towel, and twist the head on and off 10 times. This was repeated for about 15 cycles and couldn't get the rivet off. I figure if LN2 won't loosen it, then normal usage won't. But let's not stop here. I'm going to continue twisting the head on and off to see if the rivet can be worked loose--maybe the initial thermal shock had a detrimental effect that can't be seen until many cycles later. I hope to try to repeat the LN2 test towards the end of the beta testing to see if I can be successful in loosening the rivet.
Now to critique of the light. When I initially got it, I wasn't expecting to be wowed. I figure it would be brighter but when Peter put it side by side with the one on my keychain (a rev3 standard) I was totally blown away. We later attributed it to the spent cell in my keychain light so we swapped cells. Even with the depleted cell, the newer version was perceived to be twice as bright overall. Now that blew me away. I think Peter upped the ante again. He showed me some recent versions of the Peak LED's which some claimed to be bright but there was no contest. The only Peak LED that was on the same league was the 3-LED AAA version. The single AAA was a dog by comparison. It was absolutely no match for the new Arc.
Ergonomics--This is about equal to the old arc AAA. I like the tapering on the head as it gives it a more aerodynamic look but I don't think it has any other effect other than cosmetics. Knurling was just about right.
Tint--As this_is_nascar said, if you don't like a slightly bluish tint, move along, as there's nothing to see here. This one has a definite blueish tint but it is not objectionable by any means in my humble opinion. As a task/emergency light, I'd take the increase in brightness/runtime over tint any day.
Durability--I've only thrown it onto the tile a few times. The AAA cell appears to be taking all the abuse. I suspect I'll have to replace the cell eventually since it's dented enough that a few more blows would shorten it to the point where it won't make reliable contact.
More abuse to follow but I have to say that we have another winner here.