Particularly if travelling longhaul business class you’re unlikely to face many issues (apart from on Qatar, possibly Austrian). That said, assuming this is for work do you really want to systematically run the risk of having your bag confiscated and put in the hold without notice?

You’re right that they’ll just check the bag and not put you in handcuffs or anything, but why make life difficult by deliberately breaking an airline’s rules?

Interesting you say that EU bags can be larger - generally I expect US carry-ons to be larger (and observationally is what I see on flights by nationality): see the Continental vs. International Tumis, or the Cabin/ Cabin Plus Rimowas.