I have some results that have solved our issue but still reveal the inefficiency in Nuendo for recording.
After several anecdotal and strange reports from operators I tested the following -
13 - Toshiba 500GB
4 - Toshiba 1TB
2 - Toshiba 2TB
4 - Seagate 7200.14
4 - Seagate 7200.12
2 - Seagate 7200.11
2 - Hitachi 2010 build date
2 - WD Black
2 - WD Blue
2 - OWC SSD 6Gb
3 - pcie flash
Systems tested -
MacPro tower OS10.6.8
MacPro tower OS10.8.5
2 - MacMini 2013 quad OS10.8.5 in Sonnet pcie chassis
MacMini 2013 quad OS10.8.5 in Magma pcie chassis
MacBookPro retina OS10.9.x
MacBookPro 2013 OS10.8.5
MacBookPro 2011 OS10.6.8
Interfaces tested -
Internal Sata where available
eSata where available
USB3 on all systems
Firewire on all systems
Test conditions - any interface available on a system was used for any drive available on that system. Most systems had all interfaces available.
A variety of enclosures were tested, it was verified that a particular brand was good, with a good drive performs well.
Each drive was tested multiple times to verify repeatability.
Nuendo 5.5.5, 5.5.6, 6.something, Logic Pro X.something, and ProTools 10.3.8/HDX2 were all tested.
The same model drives varied substantially in performance.
The Toshibas exhibited the worst performance, rarely succeeding above 70 tracks in Nuendo.
The Seagate 7200.x were fine with 128 tracks but oddly the dot12s performed a bit better than the dot11s or dot14s. Strange.
The Hitachis were good for 80 tracks and 112 tracks respectively, still not good.
The WD Blacks were good at 128 tracks, didn't test them above that.
The WD Blues, suggested by our enclosure supplier, were good at 192 tracks on eSata and usb3 and 128 tracks on firewire.
The SSD and pcie flash were very good of course.
ProTools had no problem recording 128 tracks to any of these drives, even the 2 Toshibas that wouldn't get to 64 tracks in Nuendo.
So the takeaway here is twofold -
First - drives are varying far too much; even if it benchmarks well it may not perform well in Nuendo, Logic, and other DAWs.
Second - my original point now borne out thoroughly - Nuendo has poor record performance compared to ProTools 10/11, a remarkable change from a few years ago. This should be examined.