The only reason I didn't get Cathe's vest is that I knew I'd want to add 25-35 pounds or so to it for strength training STS legs, and it won't go that high. I ended up with the XVEST instead.
I actually have two vests - one kept set for walking or use in kickbox, at about ten percent of my body weight, and the other is set for strength training, currently at 25 pounds for use in Meso 2. For squats and lunges, and for some of the paper plate moves, I find it far more comfortable to shift weight to my vest instead of using my dumbbells. The weight doesn't swing as much, making it easier on my knees; and carrying it on my core reduces strain on my forearms, elbows, and shoulders while still letting me challenge back/legs/glutes.
