I am nowhere near the lifter that Bill Crawford, or PowerlifterJay, or Irishpower is, but I get a lot out of a shirt. Over a hundred pounds for sure. And this is from a double denim open back shirt. No kevlar, or anything illegal. I know guys who get a lot out of a shirt, and I know guys who get hardly anything out of a shirt. And I would point out that my shirts are not even particularly tight. I put on my open back shirts completely by myself. Ask BigOkie and Screwball.
What matters in this sport is what you put up in equipment legal to the organization you are competing in, under meet conditions. I would love to bench 400, 500, 600 raw. But I would much rather bench 500, 600, 700 in a meet. I do not have healthy shoulders, as a result of my sporting life before powerlifting. I am terrible out of the bottom without a shirt. I never go above mid 300's raw because I get severe pain in my right shoulder. But I just smoked a 2 board press wearing a shirt with 475, narrowly missed 500 (because I misgrooved it) and have done as much as 585 for a close grip lockout in a power rack. With less than a year in the sport, I am getting more out of my equipment than some guys I know personally who have been doing this for 20 years.
Equipment is here. I like it. This is the way it is, and for people with injuries, or older lifters whose joints are worn down over the years, lifting with a shirt is much safer, and more enjoyable.
B.