Just added a link to my post on the EGA/(S)VGA SLR behaviour, as well as some discoveries about it's latching and wrapping behaviour during the different graphics modes.

Ofc I don't think that the SLR bit would have any effect in text modes? Since there's nothing extra to rotate in text mode, I guess it would cause the same effect as 256-color mode shifting (the same pixels repeating over and over due to the same inputs being used)?

Edit: Just improved the Tseng chips to properly use the EGA emulation bit to perform the horizontal and vertical blank end properly (masking to 5 bits instead of 6 and 8 bits respectively).
Edit: Just improved the shift registers to operate in big-endian mode properly on little-endian machines, since plane 0=byte 0 of the value read from VRAM.