One can take anything to an extreme but with a high value crop like you are growing I would not be shy about jumping with both feet into valve controlled RTK and think you should also entertain the implement guidance as well.

If you have already calculated good returns from your current choices perhaps there is more to gain (although you may have picked the lower fruit already).  When you consider guess rows, and possible digging damage etc perhaps there is a lot more to gain yet.

The icing on the cake with a full RTK system is knowing who ever drives the rig will always be spot on thus taking out the subjectivity of nudging etc.  The cherry on top with RTK would also allow you to fix topographical issues like little undulations in your fields that are probably not helping size consistancy and water distributions even under a pivot but that is a whole new discussion!

I am not a potato grower but ones I have talked to say these are all issues.

Arnie