Haven't tried the Rev'it jackets but I've used the evaporative cooling vests on the track and street rides in Central Florida heat and humidity. Since the evaporative cooling effect is obviously based on water evaporating, when the humidity is very high (like in FL for 7 months a year) the cooling effect is considerably less than riding in a lower-humidity environment.
It works best for me when on super-hot track days when I soak the cooling vest in a cooler of ice water and put it on under the race suit just before going on track. It works for about the first 10 minutes of a 20-minute session. After that, you've worked up quite a heart rate and body temp that you're hot again. But when you come into the pits and take off the cooling jacket to re-soak it, you're already all wet and if you're wearing some type of Coolmax moisture-wicking top and sit in front of a fan, you'll be much cooler than without using the vest.
On long, hot street rides, even when pre-soaking the vest in ice water, it will only really cool for about 10-15 minutes and then will only be as effective as your airflow. So if you're on a sportbike with a Corsa-type windscreen, you're actually out of much of the airflow. A naked-type bike would probably work better.
Good luck this summer - if you haven't experienced your Pani in the heat and slow traffic, you're in for an experience of roasted bum and thighs!
