No harm no foul really on no FAT32 files greater than 4GB for Gear VR, since best really to encode at 720p- a much better resource fit for the split content on the Gear VR that is actually some less than 720p.
SDE is significantly less on the S6 than the N4 version. You trade off some FOV, but for movies IMO it is a good trade-off. Since I already have the Note 4, I went the much cheaper route and bought a generic Teefan set and use it for movies. I prefer it over the Note 4 Gear VR. No more front row-like turning some side to side to see the entire movie and trying to mentally filter out the SDE. I can also read subtitles more easily (for ones with smallish fonts).
Oculus supports MKV, but picky on some audio codecs. A bonus though is Oculus plays M4V files that are usually less than 2GB files, but usually very efficient 720p video that looks very good.
