Roof Complexity and slop:

There is no any limit for the roof design and its complexity/slop. However, Roof complexity design would affect the cost greatly. Simple roof line with minimum number of the hips and valley are considered as the basic roof with the minimum cost. If you are considering high pitch /sharp slop for your roof, almost there is not much difference for the cost of the prefabrication, but you might consider extra cost for assembly if you decide to have roof with pitch 6/12 or higher.

Hybrid construction:

If you are interested to have traditional looking timber framing with open design as well other feature / lower cost, Hybrid construction could be considered as an alternative.

The exterior wall (SSP panel) would be considered as the load bearing wall and post and beam frame would be applied only through interior of the design.

If you have access to the material and resources familiar with conventional studded wall frame, you might consider to have timber frame combined with conventional studded wall in order to be more economic.

Also Hybrid construction might apply to integration of the log siding, straw-bale insulation and other construction method such as ICF (insulated concrete form) blocks.