Contrary to what you often hear, 357SIG and +P+ 9mm are pretty close in power. I got that very response from the engineers at Speer when I emailed them with the question on the difference when I was hot on 357SIG. They basically said both were 40000psi loads (Speer apparently has a spec for +P+ 9mm), and bullets of the same weight would perform basically the same. Thats why I was asking plouffedaddy if he'd consider a comparison of the +P+ 9mm.
Good info there. I don't have any +p+, sorry.