Hai,
While I did take into account a spherical planet when I drew this, I didn't get too bogged down the detail of the poles in the design phase, this is because everything above 60 degrees latitude in my initial drawing are fluid. That is they are unexplored and therefor very much subject to change. Also they were hard for me to visualize outside a globe.
Now that I've started building it in Fractal Terrains, I've made a few changes above 60 degrees latitude but not many. Mostly it was to align the eastern and western continents and deal with some north-south distortion issues in my land masses. My plan is to test my polar plates in either a gnomonic or orthographic projection before I lay out my mountain ranges and start defining my coastlines.
Incidentally, I also discovered some distortion east-west when I started putting into FT. Notice the longitude lines in my drawing and you'll see why.