I think the biggest difference is the air bags - especially compared to my first MH, a 36 foot gasser.
My 2003 DP at just over 41 feet had IFS and so did my previous MH (38 feet DP)and I thought they rode great.
My current rig at 43 feet (10 airbags and shocks) has a solid front axle and I really can't tell much difference. I always say its like riding on a rocking chair, smooth and very little jarring, no matter which DP I drove.
Not much help as I didn't see much difference.
Retired Canadian Army WO (1972-2000)
2008 Holiday Rambler Scepter 42 PDQ
Toad 2018 Ford Edge w/ Patriot Braking system/Blue Ox base plate/Ready Brake tow bar.