Are old work electrical boxes acceptable for roughing in?
There is nothing in the NEC that says you cannot use old work boxes.  In some parts of the US and world there is a lot of plaster.  When doing a couple of flips in France the past year we used a tool that basically cuts a one inch line in the plaster and run electric through said lines and put in old work boxes (designed for plaster).  

The issue of how secure the boxes are is totally up to your local building inspector.  If you in any way feel that they are not safe (not secured enough), call your city hall and ask to have the inspector come by.