I've used XP for two years. I use it for seeding, summer-fallow, and harvest. In that time, I had one instance where it jumped 18". Other than that I've never had to nudge during the days work. Some of my fields take 20 minutes to work one pass, so there can be 40 minutes of accumulated drift at the ends of the field. I may need to 'shift to here' at the start of the day but that isn't always necessary.
I set my air-seeder to the exact width, chisel for fallow is set 12" narrower than the tool, combine is set 3" narrower. When using WAAS, I'd find myself doing the following: Look back, should I nudge?, look back, should I nudge?, look back, should I nudge?, look back, better nudge. Then go for a bit and repeat. I don't miss that routine at all.
With the increased solar activity, I think many will be disappointed with WAAS during the coming year.