Hi they are supposed to be implementing warning messages soon due to the number of sellers like yourself being zapped in mid edit and even scheduling posts during maintenance which of cause fail.
Their normal maintenance on Thursday evenings (thier time) is regular so best avoided. Ceating listings any time to post the same night is perilous, that is why I always try and create in advance and schedule them (which is free from Auctiva) so I do not get caught out near to listing time whether it be a local domestic priority change or an international internet hiccup.
The trouble with any auto-save is when it happens and you do not want to to happen, e.g. you have saved listing A, editing it again to be listing B by using save as new when done. But an auto save grabs it from you and just overwrites A, arrggh ! Not good, but then I think it is always better to use creat similar.
So I reckon from my experience it would be difficult to implement in particular to suit everyone.