I definitely have the same problem as you, Canadianpj.... At first I only got the graphics artefacts/hangups upon wake-from-sleep, but by now it's getting more frequent and at seemingly random points in time. And as you reported, all the crashes show logs like this one:
Oct 11 16:52:12 turmeric kernel[0]: NVDA(OpenGL): Channel exception! exception type = 0xd = GR: SW Notify Error
Oct 11 16:52:12 turmeric kernel[0]: IOVendorGLContext::ReportGPURestart
Oct 11 16:52:12 turmeric kernel[0]: 0000006e
Oct 11 16:52:12 turmeric kernel[0]: 00200000 00008397 00000474 00000040
Oct 11 16:52:12 turmeric kernel[0]: 0000047e 00000ff8 00560000 0000000f
Oct 11 16:52:12 turmeric kernel[0]: 00000000 00000000 00000002
Oct 11 16:52:12 turmeric kernel[0]: 00000040 00000000
Did it work out for you to use the build-in graphics only? I'm really starting to get desperate, since those hangups make it almost impossible to work properly.
And in case it did help you, can you give me a pointer on how to make your MBP use build-in graphics only?
Thanks in advance!