As somebody that has used both, I initially switched from Extreme Pro to the GT98 for about 3 months, but I have switched back to the EP.
GT98 is really addictive in the feel department, but in overall higher level playability the EP just wins in pretty much every category.
The string bed on the GT98 was just too unpredictable for me in the long run, I could not dial it in even with thicker strings.
edit: (If the GT98 was 18x20, I think it might be one of the best sticks ever made)
If you're looking for feel and fun, GT98.
If you're looking for all out performance, Extreme Pro.