Hey SixCats,
I only have 1 Klarus, the ST20, for now...but among my collection, I really like it. It's the slimmest among my AAs (Fenix LD20, Fenix E21, Dereelight Javelin, 4Sevens Quark X AA). Also, among those AA lights, the ST20 color is more cooler than my other AA (more white-ish). For me, definitely nice to hold in hand, though some people (my colleagues who were playing with it) felt it was too thin to hold.
I'm no expert when it comes to the technical details but i feel the build quality is nice, but I honestly like the mode on the Klarus. The ST20 has 2 modes, tightened (low > medium > high) and loosen (lower > sos > beacon). To access strobe, you press and hold the side switch in either mode.
It has mode memory on the tightened mode, which I really like because I usually leave the light on medium for tightened mode. The momentary on function (forward clicky) is a plus for me too...that's one thing I wish I had on my Fenix LD20.
For me, I started with AA lights first...then as I spend more time in CPF, so does my wallet
Because after the flashlights, came the eneloops, then came the Maha c9000 charger :duh2:
The XT series is in my list to buy next...just not sure which one I want lol. I'm in the same boat, as in, I'm liking the tactical tail switches but I'm not sure if I wanna go AA or CR123 lol