baseball:
I used the Duplicolor Kit almost 3 years ago and couldn't be happier. They still look great today. I installed new rotors and pads at the same time and wasn't in a big hurry to get done, so I removed the calipers from the car. I wanted to flush the system with new fluid as well which factored into my decision to take the calipers off. I think I had the brakes apart for a couple of weeks.
I've seen the great pictures from Boxtaboy and others using the G2 Kit and am impressed. My guess is either kit will work satisfactorily. Be sure to clean the calipers thoroughly and you shouldn't have any problems.
If I ever do it again I would probably use the Duplicolor caliper spray instead of the brush-on paint that I used a few years ago.
This is a recent picture with a glimpse of my caliper.
Best of luck,
ddb