I would not do it without 4-5 years of "Good" yield maps.  With a black box, you only get back what you send.  If there was a compaction issue or fence line removed, it could take that as a management zone.  You also need PP's stuff and your planter must plant up to a certain level of accuracy or they will not do it for you.  

It sound like to me if you didn't have a real good grip on your fields and the fields were highly variable they could pay big time with fieldscripts, but if you know each field intimately like many of use the gains will be more modest.