I have this lamp for a year now. Actually I heaved a prototype of this lamp a year ago. Anyway, what I can tell from my experience is that lamp rocks. I changed my first one for a new one with warm LED's, 5600K, because 6500K what is normal model doesn't go well with my eyes, just professional problem. I work in film and TV business as sound person, but was to many time involved in picture and lite control... maybe some other time. In short I prefer 5600K aka daylight light. Now lets say something about the El speleo. When I get first one it heaved 4 modes and different switch. The switch was a big problem because you could not gain 3A current thru that switch and not to melt it. So Zeljko went to ordinary switch but it is to big to put bigger control chip, where you can program more modes. So for now it is three modes on flood light. But if you want different power setting on those modes it can be done. On mine I have 100, 350, 1000 lumen on flood. I found that that is optimal mode settings. If I need camp light, or lower light, I always have tikka or something like that around my neck. I use it lot for filming and photographing underground, and 5600K is perfect because there is no problem with white balance on yours camera if you have it on auto WB. The electronics in camera is pretty accurate with that light. As battery concerns, there is no concerns. With big one, 9600mAh pack, I have been 4 days underground, mostly on middle mode ( 500lm old lamp ), for at least 12 hours a day. In underground camp I'm using a TikkaXP. And it was working 12h more when I come home. It was in testing phase back then. The new 7400 packs are also good. I still use first one that i have put on helmet, and was on four or five short trips ( 6-8h underground ) but it is still the same battery pack. I always have the spare in my bag anyway. And at the end, if you want the lamp, you can always customize your order, because Zeljko can program what you want. And as price thing, I think that for that money you can't buy anything close to this one. It works, it is tested in pretty rough conditions, it is waterproof and is pretty cheap.