Well this mornings run with both the 305 and 610 was on a course that typically measures from 7.28-7.32 miles. I wore the HR strap that came with the 305 instead of the 610. Why, just for testing purposes. Also, I ran with both watches on Smart Recording vs. 1 sec recording.
Results? The auto-lap GPS accuracy bug is still there. It wasn't that bad at the start. I now show GPS accuracy as one of the field on both watches. When auto-lap engaged for miles 3,4,5 and 6 the GPS accuracy for the 610 went haywire. From < 20ft to > 250ft in most cases, while the 305 maintained GPS accuracy 15-20ft.
So, basically when this problem occurs your lap pace (which is what I have always used and has been reliable on the 305) is usually off by 20-30 sec/mile after 0.25. On the 305, it usually took < 0.1 miles for the lap pace to settle down. The 610 would tell me after 0.1-0.15 miles of a lap that I was either running > 10 min/mile pace or < 6 min/mile pace when the GPS accuracy bug occured. Rather frustrating.
The distances and paces lined up pretty well for the first 3 miles actually. I was thinking that using Smart Recording would help the 610 accuracy problem I showed in the video in my previous post. However, at mile 3 it showed up slightly. Mile 4 is very obvious in the GPX track. It would probably be bigger if I used 1 sec recording. (Green is 305, Red is 610). No, I didn't do a run around in that persons front yard while running. At least I don't think I did.
Here is the HR data from using the old 305 HRM strap. The following is for the 610. Notice there seems to be some errant HR data in that first mile, but the rest looks smooth. (Note: A rather depressing HR curve for the past that I ran. Running mojo is gone)
Here is the splits for the 610, then the 305. One thing I noticed for the 610 on auto lap is that the splits always seems to occur on the 1/4 seconds for the middle laps. Don't know why. Paces line up pretty well, except for mile 5 which has that loop shown above at the start.