I'd like to add to the "less inputs, smaller lag" discussion:
I haven't looked into it more, but that's the general impression I've gotten, too. Another is the omission of OSD and hardware scaler. There were (for example) the Hazro's 27" B-model (don't remember the exact model number) and HP's ZR2740W which both had very low input lags, but were also lacking on the said features.
These were relatively OK compromises for computer usage, but deal breakers if you also wanted to use the set with other devices, like gaming consoles.
With regards to why DP being the only input option would be a good thing:
I think that logic relies on the assumption that offering only one input actually decreases the input lag (like he stated in his post). And I had the same thought-pattern, though personally I would have hoped for a DL-DVI. But if the above discussion is right, then apparently G-Sync only supports DP.
As for active 3D and G-sync:
What happens when the game hangs for a second or there's a more demanding scene and the frames decrease to 10fps? Will the other lens stay black for a longer period? Dynamic framerate would suggest that the "dynamicity" would have to apply to the 3D part, too, would it not? For passive 3D, this wouldn't be a problem, but for active, it probably requires a work-around. Or is there perhaps a safety-limit (like 33ms?), and if there's no new frames given, an old frame is re-painted on the screen? (which kind of goes against the G-sync principle, though)
Again, I haven't looked that much into it, but for a more robust system, it could be possible that G-sync is disabled for 3D, so that the active glasses can operate on static 120Hz (meaning static 8.33ms intervals), like they are now.
Disclaimer: I still haven't looked that much more into the G-sync, so it might be that I'm misunderstanding the whole design concept. My understanding was that G-sync lets the frames "update" on the screen on their own pace, not limited by the static 60Hz or 120Hz timing intervals. In other words, instead of 8.33 - 8.33 - 8.33 - 8.33 ms intervals, they could use 10.5 - 61.2 - 15.0 - 8.33 ms intervals, depending on when the GPU has calculated the next frame. The 8.33ms simply being the minimum interval.
