Good question.
Hot air likes to rise, so going up is not a strain.
Lint would settle if there was not good flow. Poor flow, or conditions that you bring up usually occur due to very inefficient roof vents. The Dryer is very capable, especially the new ones, at pushing air and any lint particles to the exterior.
For the soffit vent, it is neat, but make sure it is not near an AC compressor, or windows and doors.
Limit the number of bends.
I am fond of either vent. Not fond of the Lint Trap though for your application. Keep the airborne particles airborne with zero resistance at the termination. Thanks for asking.
Sounds like you aready watched the DryerJack video...
http://store.dryerbox.com/DryerJack--Low-Profile--Scoop-Design--Mill-Finish_p_107.html
