My 2 cents: Thanks to DannoXYZ for clearing things up for those who were in the dark about this stuff. The flex photos are great. I knew threadles stems were flexy (only a fool will doubt that...), but this massive flex is new to me. Great info.

To me, the whole question is moot. Threadless is superior in every practical sense except for the ease of height adjustment. Lighter, simpler, stiffer, stronger, easier to set up and to take apart with no special tool, holds on to the steerer more firmly without getting stuck in it. Really, the threaded HS+stem is a pitifully weak engineering product compared to threadless. Just take setting bearing preload. TL: juggling with two nuts, trying to guess how much it will tighten up when you tighten the locknut, torquing down on it hard as you can... then loosen it again to correct the setting, a couple of times. Of course it's simpler if you have two wrenches, but who buys two? T'd: Tighten the clamp screws halfway, slowly tighten the top screw. When it's just right, tighten the clamp and you're done. The setting doesn't change, and it won't loosen up later, either. It's just more intuitive. You can do it on the roadside, with a multitool. If you don't have on on you, then the next biker who comes along will lend you one. Try asking for a headset wrench...

To me, the threadless system is more beautiful as well, but that's personal taste (Who likes the look of two 32mm nuts, though???)

As to those who can't see an inch of flex in two photos and keep arguing to try and save face... *shrug*