Bro a 405 incline is equivalent to a high 400's- 500 lb flat bench in my book. I benched 420 when my incline was 350 or so.
U can't make a general statment on that, some people are stronger on the incline than on the flat bench, depends on how strong your delts are I guess. Markus Ruhl even went heavier on the smith machine shoulder press then on the incline or flat bench.
I guess the incline bench is Mikes "signature lift", as he pulls off his usual 4 plates on video over and over again. And like I said, 405 is def a decent amount of weight on the incline bench, but nothing to go crazy about in times where the raw bench press records are 700+.