Cheers man, that's made my day and it's only 8am. Lol however I can't really take any credit as until you told me yesterday - I didn't know what 'vision latency changes' even meant
Just to manage others expectations who see this thread and hope it might solve misc issues. I've only seen this problem with my rig so it could be specific to any combination of my setup.
The history is : I've always been very lucky with ED2 / DK2 being stable. Early on I took the advice of the more experienced forum users on here and aimed for a steady 75 fps in stations etc. The only way my Nvidia GTX 770 could do this was by choosing the preset LOW and turning down the Oculus quality slider. For me this made text hard to read (physically hurt my eyes).
Others with the same card were running on high so before upgrading I wandered if my PC had a setup issue. ED Beta 2.x Eagle, Windows 7, Intel I7 920 OC, DK2 (direct mode), Nvidia GTX 770 OC.
Most elements were over clocked so I considered if my CPU was bottle necking. My limited understanding is with a quad core processor like mine it had 4 physical cores. By turning on Hyper threading (took 2 mins in BIOS settings on PC boot) in windows task manager this jumped to 8. As a direct result my benchmark 3Dmark 11 went through the roof. However ED became unusable with a regular white pulse/flash effect so I turned it off again. For me personally the solution was an upgrade to a GTX 970. I still only use preset LOW but with the Oculus quality on full I find the game very playable (doesn't hurt my eyes).