Hi BobSaggy
Prior to the release of 10.9.2, some people tried the sleep-wake method of forcing the BSOD on display MBAs in Apple stores and retailers.
I was able to crash every one I tried but others found a rare one that would not crash, hence we have concluded it is a hardware issue as the software is clearly the same on each.
My 2012 MBA only ever crashed whilst in sleep mode in my bag. It always reported the error and recovered.
My 2013 MBA was stable to begin with, then began to crash in my bag(with error reports), eventually crashing with increasing frequency, even whilst sitting still reading a document, or, worst of all, in the midst of a presentation to a board of directors whilst pitching for £200k of work whilst operated by remote control wireless mouse without recognising that a crash had occurred.
This degradation also points to a hardware issue.
On the Fac ebook group, we're not calling this a fix as it clearly hasn't resolved the issue for all, just prevented it being forced or inadvertently triggered by nudging the power button when hitting, "Delete".
The fact that Apple didn't even acknowledge the existence of this issue until after the Fac ebook group appeared and made no reference to resolving it with the release of 10.9.2 does nothing to reassure any of us that they either understand the problem, or are trying to fix it.