I have a outback 295RE, 35' over 9,000lbs. Had it set up and towed perfectly behind my 2004 2500HD CC/SB/4x4 silverado duramax with bilstein shocks and torklift stabil loads.
Then we bought a 2015 GMC sierra 2500HD CC/SB/4x4 duramax. virtually identical vehicle with the stable loads but factory shocks.
hooked it up, checked out the WD, etc. and took the outback out for a trial run thinking it would be just like the 04. NOPE. no sway but not as stable as the 04 setup when changing lanes, very noticeable difference. 04 wasn't sensitive to tire pressure in the TV. Adding the bilstein shocks to the 15 helped, then running tire pressure to 75lbs front and rear helped, and needed to tilt the hitch head down one more notch. Now it is the same.
So, what seems like the same tow vehicle can act differently and subtle changes can have a big effect.