So we went back to the drawing board. You wanted feedback. We've got a lot of it
Here's how it went:
On the system upgraded to ATI 5770 - we got between 15-25% improvement on redraws for fft/spectrum and processor UI overlays. definitely there is some tangibles in improvements. Stability remained and no ditch crash scenarios observed, even in turning it on and off between restarts with running background audio.
The system with the Nvidia Gt 120's same scenario as the first ditch/crash. There appears to be a weakness in the way that the Nvidia reacts with it using the standard Apple drivers and it remains a question mark as to improvements and stability.
But with the current updated Nvidia issued drivers (for graphics and the accompanying CUDA drivers - they are separate downloads from nvidias website)
here's what we got.
With just the Nvidia graphics drivers - we got stability, no visual improvements but the crash situation was not reproducable.
With the Nvidia graphics drivers and CUDA extensions - we saw between 20-30% across the board improvements in both redraws/update stability and zero ditch/crash conditions.
It does appear that it is a driver issue and it is related to large memory conditions (the standard driver crash was not reproducible with the stock apple drivers under 8gbs installed - over 16gb or better, it was reproducible almost on cue.
There you go, hope this helps.