i have been running some outback s3's and have been happy with the product most of the time.  This past fall however i was ready to throw it out the window on a few occasions. 
I run them on the air drill, tillage and combine.  No big deal.  Last fall about 5 in the afternoon in the combine i would start to drift.  Usually about a foot to two feet.  Even late this past fall I noticed it in the tillage tractor (2 different units) it would be slow to compensate then I would lose my line and have to start over.  It only happend a couple time in the tractor but in the combine it was constant late in the afternoon.  Would run great in the morning and most of the afternoon.  Called outback they didn't say anything about satellite problems.  They asked about settings and they all seemed fine.......

If i had a baseline would this help keep my line and accuracy?  I would certainly hope so.   Just want to hear from some guys taht have 'em

TIA