I'm shooting WFTF/PCP on occasion. My 12fpe carbine only weighs about 8 lbs, so muscle strength is not much of an issue. I do plan on adding more weight to the pistol/carbine at some point. I would hope that holding steadier on the standing/kneeling shots would be the main benefit of a shooting jacket. I don't currently use a jacket or harness for my sitting shots, and the only wobble I get is from pulse bobbing. If a jacket would reduce the pulse bobbing, that could be another benefit, but I would not wear one if there was any heat issue with it. At most of my matches, optimum body temperature (no sweating) is achieved by wearing a cotton T-shirt.