For anyone caring PC mag got substantial numbers from a trio of tablets:
http://www.pcmag.com/article2/0,2817,2415809,00.asp
Antutu=36489
geekbench=4148
GLBench offscreen is 57fps
So I'd say it should do well in a tablet vs. S800. It destroys S600. Not bad. Those were devices from Feb, so I'm thinking a shipping tab would have to be optimized a little more than a pre-release product but I could be wrong. Hope someone tests the toshiba write soon, not to mention HP's and ASUS's T4 tablets.
Antutu on the Shield is impressive (though 720p, glad they didn't try 1080p on this thing, 720p gives it plenty of power for what it's designed to do) but the 1920x1200 1.9ghz ref tablet isn't far behind and S800 scores I've seen from devices show about 35k on tablets. That being said I expect S800 to match or beat T4's gpu (though we still need to see actual games benched, not synthetics to truly prove this), but I think most cpu test should favor A15. The numbers out so far seem to show this.
I don't see T4's lack of OpenGL ES3.0 as any big deal. There are no benchmarks to test it, thus no software that uses it either. In other words, NV was right to dump it to save power/soc space etc and dedicate that to what we will probably use during the devices life. I'll change my opinion maybe after a few games show up with ES3.0 in them. Until then, no point in having it yet.