I took an m193 in the plate in back once. Right over the kidney, from about 50 yds. I deleted half of this post because the rest of it could have been lawyered into some bullshit about violating a post lawsuit NDA.
I don't think I'm going to take many rounds on the plate if I do get nailed. I would think most of them would be non-center of mass hits and a lucky one or few in the plate protected area.
The backface deformation on my early ceramic plate was intense and frankly I think it was on the edge of penetration. Maybe a modern plate would do better.
It also sorta swings a bit the other way towards steel the more multi hit you are going for. I would suspect a steel plate with a Kevlar wrap around liner might take even more hits than a ceramic plate before a bad outcome.
i guess I'll finish this out by saying I think plates are like ar15's. An old m16 from bam wasn't much to write home about...and a $400 m4 today isn't either. But that doesn't mean a $1000 ar15 with all of today's modernizations is junk either. If you spend a bit on a steel plate and Kevlar spall guards it might be as good or better than all but the most premium ceramics. If you paid $34.50 for your steel plates with Krylon spray paint on them you are probably fucked.