Honestly, I can’t say that I notice a huge bittering difference either. But a) lab results consistently show about a 10% increase in IBU and b) it’s easier for me to FWH so I don’t have to watch when the boil starts and remember to throw the hops in.
Without knowing who their tasters were, I wouldn’t necessarily think their palates are less refined. Generally speaking, being a BJCP judge means that you have a more consistent vocabulary to recognize, identify, and describe things, not necessarily that you can detect things that others can’t.
And I don’t disagree FWIW. If I didn’t make a brew day checklist, I’d forget to add hops half the time, whether it was a FWH or 60 addition. As said, I FWH beers on occasion but generally bitter @ 60.
How long would a FWH last in the commercial setting? Probably well over an hour and alot longer than any homebrewer would.
I brewed a CAP with Jeff Renner several years ago. His FWH procedure is to have them in the wort for about an hour - when his sparge is over he has lunch - holding temp during that time.
I haven’t really noticed a difference with the bittering character when using FWH (for the beers I have brewed that way at least). But I do remember a long time ago I brewed one of my only Witbiers, I bittered with Hallertau as a FWH addition and the although it was a mild character, the hop flavor and aroma in the finished beer would have been enough to make you think it was actually hit with a touch of late hops. It was enough to convince me of some of what is believed to be true for FWH.
I don’t know if it makes a difference or not but I do know that when I do it, I am a lot less likely to get a boil over than when I toss a big bittering charge in when the wort is already boiling. 
Tony