Ah, thanks for your question. As I've mentioned elsewhere, I choose 'ultra' from the graphic presets, and then turn off AA, AO, Blur and Bloom, and turn on SS1.5.
With beta 1445878235, I get consistent smooth performance with essentially no micro stutters.
As has been discussed elsewhere, with each beta release, performance seems to drop slightly. I read somewhere that someone said he used to get good results with a GTX680 with the early betas.
It seems that the later betas have added code which results in slightly more overhead, in which case I begin to experience the occasional micro stutter (as tho I'm right at the edge of performance before I have to start reducing the HMD quality or something else). Fairly rare, but it sometimes catches my eye in stations and asteroid fields.) This suggests that I am right at the edge of performance (despite only seeing about 60% GPU and 40% CPU load on an external meter.)
When I say micro stutters, I mean little instantaneous 1 or 2 frame glitches when panning your head around and something happens in the background, like a new ship loads, or I bring up the menus etc.
If I was to reduce the settings slightly, I would not see a difference between the two betas, but I'm reluctant to give up that last bit of oomf !.
The difference that I see between 235 and the latest build is that the latter has better support for the OR HUD (in 235 some of the numbers just aren't there or are wrong). I know there are other changes, but they are not immediately visible. I have never had the 75Hz issue (I run triple screens in surround, so no 16:9 displays), and as I say above, the only meaningful impact on me is a slightly slower performance which pushes me closer to the edge where I might have to peg back a setting.
Hence, I wish to stay with 235. I am certain I will have to bite the bullet when my CV1 arrives as I will surely need the latest drivers.
If ED goes OR native (and we get full OR performance), that will mitigate the issue. But now, I am just grateful that I have found a combination which allows me to get back into silky smooth ED VR again.
re: Pascal: Pascal (and possibly the need for a new motherboard to take full advantage) is the subject of a future purchase, but I want the best I can do for the time being ;-)