I use 4sevens CR2 as the smallest reliable keychain light. It's always with me.
I also have 1-st production 4sevens Preon 0 which is a not reliable for me.
So Mini CR2 is very powerful 130L (warm tints) up to 200 (new XP-G2) on a high level for 40 minutes. Direct drive though.
What will be the reason for me to buy Quantum DD ?
How long are run-times for each level,
how fast is charging of its battery
What are its weight and dimensions ?
Would like to see pics of comparison with CR2.
Runtime on max is around 100 lumens for about 8 minutes, there are no set "levels" because it is infinitely variable. Since it goes lower than any other light I have, it will most likely last quite a while when running on the lower end.
I've only charged the battery a few times, but it has charged in less than an hour each time.
Not sure of its exact dimensions but its TINY.
Here is a size comparison.
From left to right: 10180, CR2, CR123A, Quantum DD, Nitecore EZCR2w (sorry, dont have a FourSevens MiniCR2), FourSevens Ti Preon1.