We went on a group street ride back in August. I was on my 2016 Duke 690 (a single) another friend was on a 2019 Duke 790 (parallel twin). Late in the ride it was obvious his legs were cramping. I offered to switch bikes cause earlier in the day I sat on his bike and it was obvious the 690 had "enduro/adventurer" ergonomics while the 790 had more "sport bike" ergonomics.
I was surprised the 790 wasn't hugely faster than the 690, at least up to 80 mph. The 690 felt faster up to 60 mph. I suspect that above 90 mph the difference in available acceleration would have been considerable.
I did not detect any aspect of the 790 that made we want to get one, even before that ride, I really thought it would be a better bike.
I see where KTM is coming out with a 390 adventure bike.