There are a few minor points, pro or con, that have been touched on before, particularly since this idea comes around roughly every six months or so, but ultimately this idea has one huge disadvantage:
A lot of people
talk about it, but almost nobody actually
tries it, so they can tinker and fine-tune and see how well it really works. (Experience being more convincing than speculation.)
I don't think it would work well for
me, for reasons I expressed on the other thread, but if you think it would for
you . . . do it! Ask TBONE and Becky about putting up some trial ads to see how they work, and go for it. And afterwards, report back.