dang, that is overkill for the posts and stringers! we usually only use 6x6 on the corners, and 2x4 for the stringers.

as far as how it holds up, either should hold up well to weather as they are made for outdoor use. you really don't need much stregth unless you plan on climbing them fence alot. the frame of the fence is the strength, not the vertical boards.

my concern would be how bad are they going to warp, they are designed to be attached to studs every couple feet at most. so you may have to put a 3rd stringer in the middle to prevent warping. i am unsure of this, but that would be my question.

Thanks for the feedback. It is WAY overkill for the fence posts but keep in mind I'm using the posts from the 4ft retaining wall as my posts rather than sink additional 4x4s. Regardless the city is requiring this structure. (more government is supposed to be better, right?...) I also plan to use 3 stringers, as you said, just to make sure there is no warping.

Two words - Heeaaaaa Vyyyyy!