I just got a pair of weightlifting shoes. It didn't increase my back squat as my weakness is at the top, not the bottom, although it's made my squat a lot more solid. However, it did increase my front squat by 12.5kg, because I can stay upright more comfortably and have a stronger push. I did my two FSquat sessions 2 days apart, and in the session with the shoes on, I was already exhausted from a long & heavy MP and back squat workout. So I didn't get stronger, but could lift more weights because of the shoes.
Have never used shirt or wraps or belt so I don't know.
On the topic of using equipments, I came across this a few days ago:
http://startingstrength.com/articles/baby_bathwater_gear_gibson.pdf
I know there are people here - great lifters and coach - who are against the use of a belt. However, I feel that the argument for the belt presented in that article - allowing your own ab muscles to work harder & lift more weights - is the same as the one for weightlifting shoes. The shoes allow my legs to push harder against the ground and improve my form, which results in more weights lifted. In fact, it's the same as using chalk: chalk allows my hands to grip onto the bar tighter, so I can deadlift more.
I think that chalk, belt and shoes are in a very different category to shirts/suits and wraps. The former only enables you to make the most of your own muscles, and it's still you doing all the work. The latter actually do the work for you.
Hence I think that the former group belongs in RAW and the latter doesn't.
I don't think anyone NEEDS belt, just like nobody needs the shoes or even chalk, but I don't understand the argument against the belt while accepting shoes and chalk.
Feel free to enlighten me.