Having ditched them for 26x2.25 Maxxis Crossmarks(my favorite tire for dj/pumptrack use now). I figure that I should post some thoughts on them(Not the crossmarks).
Pros:
1: They do their intended job really well which is to grip packed dirt and pavement like glue.
2: Fairly light there's lighter.
3: 80 psi, which is good if you decide to go on a street session or to a skatepark.

Cons:

1: Wears out quickly, not suitable for a rear tire. In 3 months, I went through 2 G1's on the rear wheel.
2: If things get dusty, they slide extremely easy.
3: Very easy to roll them off of the bead if you run any less than 60 psi.
4: Not the cheapest tire out there.

Overall, I liked the G1 as a front but felt it lacked in ability as a rear on dirt but is great in a skatepark. Fork a park tire, I would get them again. They would stink for a trail tire.