Also converting to verts will allow you to "domain" shade your object by selecting faces and assigning shaders to each polygon group. (cant do that in spline room)

One other thing is, from what I see of your models is try to attach verts across those n-gon faces (try to cut them into 3-4 sided polys) this will help eliminate much of the distorted ripples on your edges.

Carrara 7 Pro, Anime Studio Pro 8, Hexagon 2.5, Zbrush 4.6, trueSpace 7.6, and Corel Draw X3. Manga Studio 4EX, Open Canvas 5, WACOM Cintiq 12WX User