Business pax mainly travel with an overnight bag and a laptop? Mainly in J or F.
Not in my experience. I've very rarely travelled in J or F unless upgraded by the airline, even when working for large, well-heeled companies. And quite frequently I find myself travelling next to someone also on business. Wish it weren't so - but it frequently is.
Doesn't mean I don't travel light though, and there's still a huge time advantage to be had with no bags to pick up on arrival.