I've always operated under the assumption that "May sign if the deal is right" and "Undecided" have questionable sign-ability concerns, and "probably won't sign" prospects are doubtful.
If you take a low end doubtful prospect in the first round because you are gambling on receiving the type D compensation pick in the event they reject, it might be worth a try. You run the risk with a doubtful prospect that their initial demands will be 7 million or so, and they either accept or reject the your offer, rather than simply turning you down and coming back with a higher one.