As previously stated in the thread, I did order the A1 EOS SS. I like it very much in terms of build quality and brightness. As I'm not much of a flashlight expert, I'm going to post the things I like and dislike about it so far. I'm a bit anal, so be prepared. :D
Size is good, it fits on my keychain well. I've only had one incident of the clip coming off in my pocket, but overall I have no worries about it. I'm very picky about the size of my keychains, and while it adds a bit of heft to it, I'm happy with utility it provides.
Low mode is not really usable for me. Even in complete darkness, it provides very little light. I would have preferred just a medium/high setting, or a low with half the lumens of medium. That said, medium is great, and I tend to keep it on this mode unless I feel like impressing friends with the little guys brightness.
The twisty method has no issues of coming on while in my pocket, and the threads are very smooth so the entire motion feels solid. This part I'm very happy with. The part that displeases me would be the fact that I notice mode skipping sometimes when I twist the light on. Many times the low mode is skipped and I find myself in medium. At least I think it's medium! I'm not sure if this is an issue with my twist motion, or if it's inherent of twisty flashlights.
The finish of the light is very nice, but the clip scratches the twisting portion of the head every time you turn it on or off, or even remove the batteries. It feels like a poor design decision, especially when it cuts right through the ITP logo. The portion that holds the clip onto the flashlight also scratches the bottom of it if you move the position.
Overall I love the light, and I can see that this hobby is going to continue to extend. My wallet is already feeling pressure to expand into a collection of lights.
Thanks to all for the recommendations and overall assistance in finding the perfect keychain light for me. I also hope my thoughts on the flashlight may help others in the future. :)