Need is really the wrong word for this kind of thing for most of us. Certainly for me. That said, I got a Lion Cub from lighthound.com and I am developing an emotional attachment to it?
It really is an incredible light. The user interface can be changed so you have two choices of interface. I found I like UI1 which has 5 preset levels and you can set it to automatically come on at the last level you used. When on at that level it can be sent to full power with a single push and hold of the button. For me that is a perfect use since the second or third lowest level is great for most use and that is what I have it come on as. Of course you can also preset it to come on at the highest level if that is what you want.
The other user interface lets you scroll through 64 different brightness levels. I find I dont use it as much but you can change to it whenever you want. The flexibility of the user interfaces is a great feature.
I also really like the way it looks and the ergonomics of it. I cant compare the brightness to the HDS, I have asked about that several times and not really gotten an answer. I dont have an HDS but have compared the Lion Cub to and E1L, E2 body with KL4 head and an A2. The KL4 seems to put out more light, but with less throw than the Lion Cub. The E1L is less light (lots less) and less throw. The A2 incandescent has more throw. A seems close in terms of total light. This is all eyeball based.
The Lion Cub is now in my pocket and the Surefires have been place in my backpack. When I reach for something to carry it is now ALWAYS the Lion Cub.
As far as the warranty, I would be very surprised to find any company that warranties something that was user modified. I had a salesman very seriously tell me once after I jokingly said I was going to paint thunderbolts on the side of a large scientific instrument that it would void the warranty on the instrument (which cost a quarter of a million bucks) or that it the warrantly had expired that they wouldnt honor the service contract (which they charged 25 grand per year for). If you take something apart you almost always really do own it.
In any case, I am enormously pleased with my Lion Cub, even my wife went from "what the hell kind of flashlight costs $175" to "wow, that really is cute".