Hmm? I thought the L2 was only regulated on low. Am I remember the wrong info? Obviously, I don't have an L2, but I will say the regulation on the L4 blows me away. I've only had it for a couple of months, and I'm still on the first set of batteries. Of course, I don't use it as much as some other lights I have, but I know it must be close to dropping out of regulation and every time I turn it on I'm always amazed that it's still at full brightness. I checked brightness of the used batteries against new ones, and it's the same. Really, really amazing!
Edit: Just starting thinking/remember.... I think I remember the pointlessness of a regulated low being pointed out before, as it would just be a waste of power at that level, so maybe regulation on low isn't what it has. I also think I remember people saying that the L2 might be a little bit bright initially, but after a very short while they appear to be exactly the same. <--That's what made me think that perhaps the L2 wasn't regulated on high, beause, reportedly, the brightness lessens a bit after a short while. I guess that only says that the regulation isn't as good as the regulation in the L4.