Best running watch for ultrarunners

I've added some ultrarunning specific recommendations for running watches 
http://fellrnr.com/wiki/Best_Running_Watch#Watches_for_Ultrarunning

GPS Accuracy and Garmin 620 Firmware

The Garmin 620 has some well-known GPS accuracy problems, which were highlighted by my detailed GPS testing that analyzed thousands of data points. I worked with Garmin on the issue, and the resulting firmware upgrade has radically improved the GPS accuracy (the details are under a Non-Disclosure Agreement.) You can see the improvement in the info graphic below, which has two entries for the Garmin 620, one before firmware upgrade one after. You can see the underlying numbers at GPS Accuracy Testing and there's an even more detailed breakdown at Detailed Statistics for GPS Running Watches. As a result of this testing I've updated my comparison of running watches, and my review of the Garmin 620. 

I was concerned that this firmware upgrade might have been optimized for my testing, but if you look at the two images below you can clearly see that the GPS tracks with the new firmware are far tighter and more consistent. (Note that the 620 actually has two firmware installations, one for the watch functionality, and one for the GPS. It's the GPS firmware that needs to be at 3.30 or above.)

Garmin 620 with Pre-3.30 GPS Firmware

Garmin 620 with the new 3.30 GPS Firmware

Supplements required for the Ketogenic Diet

Unlike most other diets, the Ketogenic Diet does not provide all the nutrients required, so I've included a brief overview of the recommended supplements for the Ketogenic Diet. 

Saucony Kinvara 5 Review

Here's my review of the Saucony Kinvara 5, a comfortable and lightweight shoe that's part way between traditional and minimalist designs. I've included comparisons with the Hoka Clifton, Altra One2, & the Saucony Virrata.  (I've also updated my table of shoe data to be sortable and a little more compact. I'm currently taking a break from shoe testing to review the scientific research on shoe design, which is fascinating.)

Skechers GO Bionic 2 Review

I've come to really like the Skechers GO Bionic 2, a lightand flexible zero-drop shoe that's great value for money. This is the shoe that I expected Nike to make as part of its "Nike Free" range, but they never did.