The 165 x 16 wide track has 30 sq inches more track than the poo 174 15 wide track. Not sure you can get any closer for apples to apples.
Your math is correct but roughly 45% of the track length is typically in contact with the snow. Snowest compared actual track contact with the ground and there was mild variation. Considering length, the Poo will have more track length in the snow and doing the math places them less than 5 square centimeters difference.
Either way, as stated the fun meter should be outstanding with both! Best option is get one of each...