You might try sending to the trial then - would probably improve your ratio, but of course the payout on that is less. But you'd get rebills (hopefully!) to make up for it.
I don't think there's a concrete answer to the sponsor content question. (I almost always use it though) There are pros and cons to both sides of the argument. A mix of sponsor and purchased content is probably best, which one depending on the site you're promoting. All IMHO, of course
