J Ley did not use a GPS (the GPS info was added after his hike and the first set of maps). For various reasons, I did not use a GPS either.
As for SoBo vs. NoBo, like most things in life…it all depends. There is no best.
Many people going NoBo do have to flip, go through a snow slog in the San Juans or go lower. GNP is most definitely a more dramatic finish than Mexico…but the finish points aren’t the trail. 
SoBo? In a normal winter, the snow does not come (permanently) until about Oct 1st. You have a good chance of doing the San Juans without a snow slog. Of course, in 2006 it came about 2 wks early. In 2007? Came almost a month later. Luck does indeed play into it (NoBo or SoBo)
There is no really easy way to do the CDT. A good strategy may be to section hike the CDT in two years. Allowing a hiker to pick and choose the optimum times to hike the trail. San Juans at the height of wildflower season? Glacier in mid-August when a touch of fall hits? Etc. For similar reasons, a Flip-flopping also works well.
I agree with the poster above… “Think about you are working for”. A wonderful journey? Some memories? Time spent in the outdoors?
Debating GPS and its use, water filters, purity, etc. is stupid. When hikers get together, we discuss memories, friendships made and sights seen. No one talks about NoBo vs. SoBo…we talk about the next hikes we want to do and other journeys taken. Some of us like to go outside every now and then. 
Paul Mags