Kel, A big part of the problem is we aren't starting with a clean slate and users or entities with a considerable investment in older GPS datums don't want to change. But still, the first thing we need to do in order to make things compatible is to agree on a method to define exactly where in the world we are when we set the A point. Then if we're baseing our B point on an imaginary point like the north pole, it helps if everyone can agree on just exactly where in the world that point is. Fancy term for all this is 'GPS Datum' , as in NAD27, NAD83, or WGS84 to name just a few. If you want some reading that will make your head hurt, take a look at this page: http://www.fs.fed.us/database/gps/datum/methods.pdf

So now, if we can indeed agree on a common start and end point to the 0° A-B line, then just how far a parallel swath method will vary from a wedge shaped swath method is going to depend on how far we are from the pole that defines the end of the 0° A-B. In my case, I'm 2,904 miles away from the north pole. If I set a 0° A-B along the west edge and work a complete section that's a mile long and a mile wide, when I get to the east edge, my A-B will be missing the pole by 5,280' or one mile. 1 divided by 2,904 gives you the difference in miles which is a number with a decimal and a lot of leading zeros. Multiply that little number by 5280 to convert it to feet and we are left with 1.81818 feet further east than a wedge shape swath system will have the east pass on a full section.

As for coming up with a system that will make a wedge and parallel pass system work together, I don't think it is possible. Kinda like trying to push a square peg into a round hole.