Actually if you look at the median GFXBench scores (which is statistically the score that most SGS4 devices would be centered around), the S600 variant in SGS4 has a GFXBench 2.7 offscreen (1080p) score of 15.3 average fps and a GFXBench 2.5 offscreen (1080p) score of 40.7 average fps.
All device scores fluctuate heavily between different runs and typically the highest official score is taken for the final placement. Of course highly convenient that there's only ONE T4 based device now in the database and for a quite limited time, which serves your purpose pretty well to even further bend reality until it gets even more ridiculous.
So in comparison to the typical S600 variant in SGS4, the T4 variant in SlateBook x2 has ~ 12% higher average fps in GFXBench 2.7 offscreen (1080p) (which again I consider to be statistically not very relevant right now due to the graphics settings being beyond what this generation of ultra mobile GPU can smoothly handle), and has ~ 23% higher average fps in GFXBench 2.5 offscreen (1080p).
See above. It's definitely not my fault that T4 has such a lame design win amount, is late or stars didn't allign in NV's favour. But thanks for actually proving my point over and over again.
As for 4x MSAA, that is about the last thing that is needed right now considering that these high end ultra mobile devices have 4-10" 1080p screens with GPU's that struggle to achieve playable framerates at these resolutions with high detail and no AA (let alone 4x MSAA), so no, the S600 variant of SGS4 will not be playable at high resolutions with high detail and 4x MSAA (and FWIW, T4 should achieve 20-30 average fps offscreen with 4x MSAA enabled in GLB2.5).
It's not needed because the minority report of a Tegra market share can't enable it up to T3 since it isn't possible and while it's present on T4 it takes a quite heavy performance drop compared to any tile based GPU out there where it's in the majority of cases nearly for free.
There are top tier mobile games that either come with MSAA enabled for select devices, so it's definitely not anything absurd for that space. It's just that it isn't convenient obviously.