When it comes to LED there is a lot light and also a lot of shadow. Its hard to tell if LED can compete with HID in every regard. But I guess in most points it can today. One of the biggest Problems of LED lights is the quite diffuse beam pattern. Some lights have a solution to overcome this like the VB-50, but therefore it sacrifices the Corona and spill light. Variable focus is other point. Most LED light are fixfocus lights. It´s up to you to decide whether you need focussing or not.
I´m the one who did the diving light test lucca mentioned some posts (German Diveinside) before and so I was allowed to have a closer look under the hood of many diving lights. I would subscribe the most of lucca´s points, but not all of them.
Nevertheless there are very few guys out there with such a differentiated point of view about LEDs. :thumbs-up
Looking at the comparison Light monkey LED or HID the choice would be not too difficult for me - I would take the HID, cause I consider the Ostar as completely outdated. Too less efficiency and too much emitter surface leading into a less bright beam. I wonder where they do buy these emitters, cause they´re out of production since two years now.
Moreover I dislike LED light with Delrin housing - with that the heat has a really hard way into the water and this with 21W?
But there are enough lights out there that are brighter than any 21W HID. The drawbacks often are no variable focus and/or diffuse hotspot. Like I always say - you can not have everything. Look where´s your emphasis and choose wise.
When looking onto the energy storage modern Li-Ion canisters are fine, cause they are easy to carry and smaller in comparison to NiMh tanks. But when I go diving and I like it the safe way. Building a multi cell pack with Li-Ion, especially the problematic Li-Po and Li-Co chemistry, needs very high attention to the safety protection circuits holding the Li-Po cells away from blowing up. I would like to know more about these circuits used (ballancer yes/no..) before I would grab such a canister and go into the water. I am not convinced that every canister that is sold, is safe enough for diving.
Information is an important point and often manufacturer are very reluctant with that. I good example are the lumen ratings I am reading. I would guess over 80% of them are false. We tested eight diving lights last time and only one of it presented a real measured lumen rating. Most times only the theoretical maximum LED lumens are a totaled up, ignoring every optical loss of the light design. Measurements show, that the real lumens are around 40-50% of the theoretical maximum. And who whats to buy a car with 100 PS when it only comes with 40 PS in reality?
So what I would like to say is, be more critical and check numbers if they are plausible.
bye,
Mike
( wish I have acess to all these lights too ;-))) . 
