Ability to select free curves in Freeform Blend and Profile Blend
The Surfaces > Multi-Surface Blend > Freeform Blend 
and Surfaces > Multi-Surface Blend > Profile Blend 
tools now let you select free curves as input. If the curves are tangent continuous (G1), you can select several of them for each side.
If a rail is made up entirely of free curves, that side reverts to G0 Position continuity. As well, Edge align is not possible on that side. If a rail is made up of both free curves and surface curves, then up to G1 Tangent continuity is allowed on that side. Edge align can be attempted only for the surface curve sections.
New Crown option for Freeform Blend
When building freeform blends with continuity set to G0 Position on both sides, the crown option lets you add small amounts of crown to the flat blends. Turning on Proportional Crown gives you access to the Crown Value slider. The slider ranges from -0.25 to 0.25, but larger values can be entered into the field. The crown value controls the height of the crown, and corresponds to a percentage of the distance between the two rails.
Position continuous freeform blend without a crown
Position continuous freeform blend with a crown value of -0.2