I work elm a LOT, as much as all other woods combined. I also vote to try it, but I will say that elm seems to lose it's hardness long before it looses it's toughness as it decomposes. Like, I mean I have seen it completely useless, but it would fold instead of breaking.
Another thing is that elm actually seems to always be full of stuff that eats it. I have cut, roughed out, and left bowstaves of red and American elm in my garage, dry and clean over a couple months, and then had TINY grubs drill TINY holes all through it when I debarked it. In fact, even barked staves succumb if I leave it long enough. Pick it up, tap one end on the floor, and a cloud of fine wooddust (and beetlegrub poop) shakes out.
I bet money it's infected with those, because they seem to live in the bark and get active as soon as the wood dies. So before the eggs hatch or the grubs grow, rough that stuff out and spray it or heat treat it to kill em. I have actually shot in a bow once, left it a few weeks before final heat treating or sanding and finishing, and come back to have it literally delaminate between the summer rings. ALL the winter growth had been eaten by bugs, and the separated layers were covered with tiny squiggles.
Anyway, point is, it's all about how far gone the tree was, but jump on some preventative measures while drying it, then see what you got. Straight, healthy, knot free elm is a joy to work with.