I have had both the 15B17CB and now a 25B175CB and there is a significant difference in their towing with the same vehicle. The newer 17.5 tows just like a "drunken sailor" as said previously. The older 17 towed really nice and obviously the weight
distribution of this trailer is a little better than the newer version. Plus the tanks were mid and under, where the newer 17.5 has the fresh water tank inside the rear sofa.
I have a WD hitch but without the sway control and it makes little difference to sway. I too have been looking at the Andersen Hitch and its on the To Buy list for this coming spring.
I did find that I have installed shocks to my trailer axle
and the difference is unbelievable. It has brought the sway into control and now can cruise easily at highway speeds without the regular white knuckle two handed life or death grip on the wheel and looking at the next exits RV park as the settled for destination. I highly recommend that modification and it will be first up when we upgrade to a 21' BF.
Hope that helps!