Good one Timba. My biggest fear isn't the bear getting in the tree with you although it's right up there with a sow with several cubs in tow.
I have had cubs come into the bait with a sow. That's bad enough. On another day I had the cubs run back into the woods where I can't see them visually and then appear and come back again for more food. I know the sow has to be there. She's there aware of you and you don't want to alarm her or excite the cubs to bring her charge into the tree with you.