I have some geometry with arcs unfortunately. We cannot use arc geometries, so I'm working on a tool to convert them to straight lines.
When I'm done, I'll post the py script if that helps you.
But I am not convinced that only the geoms with arcs are the problem. But I'll investigate this asap anyway.
I am working on a tool to export all data to shp before arcmap closes, and test for differences when i start it again. So far, nothing concrete, it seem completely random to me.
I've also contacted our ESRI Support. Waiting for a reply.
btw: I am using esri_binary geom type because geometry/geography loads our sql to about 75% CPU per user !