As far as I can remember, at least from Boston, the most succesful Rule V choices have been mediocre pitchers such as Vaughn Eshelman and Chris Reitsma.
However, I think this is great in OOTP. There are a few players I would pluck from rival CDL teams if I could because they aren't on the big club and I would put them on my team for a whole season, most notably Johnny Abrego of the Houston Astros.
http://www.cdl.ootp-leagues.com/files/p42.html