I think the difference for you will be like night and day.  We have had several fifth wheels and 2 motorhomes.  The first motorhome was a gas which was a nightmare to drive.  It wandered all over the road.  The second was a 39' diesel pusher which was much better to drive but would still get some pushing by trucks and wind even after I added Koni shocks, front and rear stabilizer bars and a Safe-T-Plus steering stabilizer.  Getting rid of the Goodyear tires also helped some but even after that I still had to pay attention or it would wander a bit.  
When we changed to our current rig 2 years ago I was absolutely amazed at the stability, even with the passing trucks and side winds.  We did get some chucking which I addressed by adding a set of Air Lift suspension bags.  My mistake was trying to get by with a truck that would do the job but pushed the limits.  We are trading in our 2012 GMC 3500 single rear wheel for a 2015 dually.  I suspect the ride will be even better especially with the Hensley BD3 air ride hitch I recently got.
Craig's wife and mine must be related because mine was very unhappy at first.  She loved the freedom the motorhome gave her going down the road.  It took a while but she is over it and loves the room and comfort the fifth wheel gives us.
You made a really nice choice for a rig.  You will enjoy it.