Reading this thread made me nostalgic so I got some of my older lights out and tossed a battery in to fire them up again. Excluding the smaller AA/AAA Arc flashlights, buying and selling, I only have a few remaining. All except the blue one has been carried and used. I typically don't buy a light to collect and only admire, but put them to use. I made an exception for the blue Arc LS.
Arc4+, Blue Arc/Lumileds LS, Arc LSH-P, and my Arc6
The HDS is what first got me into this mess. I saw one in a banner ad on a webpage. I had already clicked past it, going back brought up a different ad. I had no ideal who made it, just remembered what it looked like. Then I spent a great deal of time on eBay searching for that flashlight that I had a fleeting glimpse of in a banner advertisement. Took me a while, but after searching for "flashlight" and scrolling through page after page I finally saw another light like the one in the banner ad. I've bought and sold quite a few of these. Actually just realized I only have four HDS lights. As was the same with my Arc flashlights, only one of these hasn't been carried, second from the left with the 2x123 battery tube. After looking at them, it's pretty evident since the lettering still looks new on it. All of the others have been carried and used quite a bit. Sometimes I wish I had kept all of them that I've had in my possession, but that's greedy. I couldn't justify having so many. I do regret getting rid of all of my U60's, but they commanded the higher asking price, so I sold.
HDS B60LE/2xAA, HDS B42XRGT/2x123, HDS B42XRGT/1x123, HDS Clicky 170 LE
As for the later lights, the Novatac series, I had a couple of them. Sold both and never replaced them. Sometimes when I see one go up for sale I think of picking it up for "the collection" but then the thought fades away as I know I wouldn't use it and it would simply sit in a box, wasted.