here's what i have personally witnessed....
Davey Boy - pretty accurate. never saw him do a max single, but 5 for 10 was a common workout for him
Road Warrior Animal - i spotted him doing close grips with five plates and a ten per side. a few reps and perfect form. so 550 seems low for a bench single.
Chris Benoit - trained with him many times before he made it big. he was only about 230 at the time, but could do reps with 4 plates. he never touched his chest tho, which always bugged me. two inches shy of a full rep.
Bret Hart - during a very short period that he was trained by Grant McReynolds, he could do a four plate incline. wasn't that strong through most of his career. he has a membership at my gym currently.
Dynamite Kid - could bench 5 plates, but shouldn't have for the size of him. i think he could tap into some kinda psycho- strength.
Hawk - wasn't near as strong as Animal, but 5 plates woulda been pretty easy for him.
Steve Blackmen - big and lean, but never saw him train very heavy. when i was 20 he spotted me on a 350lb. attempt. the rep took me about 35 seconds and his hands never came off his hips. i think the only reason i made it was i thought i would die before he woulda helped. when i racked it, he looked totally unimpressed, and said 'i'd say thats about your max'. lol
Jim the Anvil Neidhart - one of the most truly powerful men i've ever met. even at 50 he could walk into the gym half drunk, and pause bench 4 plates like nothing without a warmup.
Triple H - trained at my gym once. 3 plate bench for a shaky 7 reps. surprised how weak he was. (coulda been a downtime for him, i'm sure he was stronger at other times).