Omni-star will get you that 2-4 inch accuracy.  We have a Beeline.   Like any Non-rtk system, it will drift over the day.  Youll still get your straight line, though it might be 10 or so inches of from your last past.

Ive talked to guys around me with JD or trimble, none of them are perfect.   This Autofarm system has my attention, though Im not willing to spend any $ on more 0guidance in the next few years.   Hopefully by then it will truly be "dumbed down" to my level, Im a 4 button guy, any more and it takes away time which could be used to make money.

Good Luck