I'm also experiencing crashes when trying to work with mesh. Uploads go fine, then when I try to edit the mesh, I crash. Usually working with them on Aditi goes fine; the crashes mostly occur on Agni.
I'm using the SL viewer, version S3-3-0-251182.
Frankly I think we have a bug here, but good luck with reporting it.
There are other things I've noticed about meshes:
>>A number of mesh garments in one location causes tremendous lag.
>>I got so frustrated with trying to handle a mesh I bought that I asked a friend to delete it just to get rid of it (is the asset server somehow involved?)
>>The Level-Of-Detail deteriorates badly with distance. Curved surfaces seem to fare better than flat.
As annoying as sculpties are, I'm preferring them these days.