Here are a couple photos I took of a hackberry longbow I screwed up. I think it might of been 60# or 70# @ 28" I think, but I am not super sure.
Hackberry is extremely strong in tension, and it is my belief that this plays a good part in why it is generally accepted to be the most steam bendable wood. The fibers are very strong and hold together very well. I had a hackberry warbow I screwed up a couple years ago, and I was trying to break it, and it wouldn't break for nothing. I was jumping off my porch onto the tip, and it was "pogo stick"-ing me back up on my porch! It also grows extremely straight most of the time, and with almost zero knots. If I had a way to mill me up some, I think it would be excellent for backings. It would be so easy to get perfect straight grain. It is also almost always pure white to the pith 99% of the time, so all the backings would come out nice and creamy white, where as with hickory you got all that brownish heart wood.