We thought about it. When we first purchased we considered buying one to share with my sister and her husband. However, the BIL lost his job right about that time and they decided against it. Since he's found and lost several jobs since then, we're kind of relieved that we just went ahead and purchased on our own. They know they can use it any time they want to anyway.
I would still consider the idea, but would make sure it was with someone that I knew well and trusted. You would want to have a written agreement as to who does what work, who pays for what, and who uses it when. I think it's a real good idea.
A good traveler has no fixed plans, and is not intent on arriving. ~ Lao Tzu