Yes Ken's blog has a great write up and he is now on about the 4th iteration of the clamp, using magnets which I am about to also switch to.
I have tethered both the S2 and S3, both the i5 version with 8GB of ram and 256GB hard drive. I prefer the S2 since I find even the i5 S3 seems to run a bit hot in my environment (spring, summer, and a bit in fall)
Overall a great solution, not too much to carry in the field and the ability to preview in C1 "priceless" especially if you are using a tech camera in the field.
The latest Surface 3, (non pro) would be excellent here but it's only shipping with 4GB of ram and that's IMO not quite enough, but I would still like to try it.
The S3 pro screen is considerably larger, but it's also denser screen resolution and thus it's can be a bit hard to read with older eyes like mine. The only real issue is the screen on either unit as they are mirrors in the sun and you will find that you want to remove the unit from the clamp while tethered to get it out of the sun. Ken's latest clamp with magnets allows doing this with only one hand. It's a great idea.
Paul