AF speed is fine from the camera end. Lenses vary. The Tamron 18-200mm has very slow AF, like the 18-200mm Sony. But the AF is damped so you can shoot video and it never jumps suddenly. It will track video with live AF very smoothly. The penalty you pay for this is a different type of AF behaviour to the 18-55mm.

David

I can't compare focus speed to the Sony - the Tamron is not fast at 200, that's sure, but somewhere there was a video showing that the Tamron is still faster than the Sony. The issue is, that due to the shake, at 200mm the camera has a problem to find some contrast. My trick is to half-press the shutter to activate VC and then it locks much quicker. And then, I have the NEX-5, 5N/7 should be faster with AF. In any case, an 18-200 is always a compromise, it was the same with my Sony A-mont 18-250.
Btw, I am now nearly A-mont free, sold the A700 and CZ16-80, just a beercan remains. I was sure to get a NEX-7, but since the A57 I think there might be a downscaled NEX-7 later this year, with the 16mp sensor.

... and that happens to be the NEX-5N

Thanks for all the info. For a long time I have hoped to find a smaller, lighter travel kit and I sort of thought the NEX 7 might do it for me. From what I am hearing though it is not the one. I know my use very well and the situations I often shoot in. I guess I must stick with a DSLR for awhile longer. I don't care about high fps, 1fps or even 0.5fps is okay for me. I don't care about video (but don't care if it is there since I might use it from time to time if I had it). I don't care much about great tracking focus for fast moving subjects. Of course, if the camera has all that then that is okay, just I won't use it. I do care that the camera can quickly and accurately lock on to focus in various light conditions, the IS system works well, and it isn't too big and heavy though. Oh well, maybe next generation there will be a NEX that is closer to what I want.