I had a Siberian elm at my old house that I cut down. The wood seemed very brittle and every breath of wind would litter my yard with broken branches. I started to save a stave or two for a trial bow but decided that it just didn't seem to have any weight or hardness to it at all. It seemed porous and spongy. The wood looked like it might have been pretty though with the dark hardwood, rich grain and light sapwood.
It's to my understanding that the Siberian elm was the cure all for the American elm die off from the Dutch elm disease. Many people soon found though with all of the dangerous, failure prone branches that they didn't live up to the American variety.