Got a solid 60fps (i have the 59Hz issue) average at 2560x1600 (hooked up my Dell U3011). GPU usage on my cards remained in the 70% range during my latest session:
I moved Grass down to Very High from Ultra, but kept everything else at max. Using 4x MSAA + FXAA. In NVCP I went to the GTA V profile and enabled 16x AF, Prefer Maximum Performance, and forced Vsync and Triple buffering. The 60fps was in the desert or city it didn't matter. I flew a bit, completed some Trevor missions, and drove from through the country side all through LS.
I've now tried and test the game in with 3 different monitors and resolutions. My preferences:
1. 4k
2. Dell U3011
3. ROG Swift
4k is first because the game looks damn amazing when running at that resolution. I put the Dell second because the colors and the size of this monitor really make GTA V pop. Swift last just because it's not as "in your face" as the other two options in terms of wow, but it is still great. GSYNC makes things nice and smooth.
I stopped using Precision X and went to Afterburner for my overclock software and OSD. Since then and the patch, I have not had any crashes. I've read of others having crashes will aiming out of windows of vehicles or heists, but thankfully I've experienced none of that.