I was asked a few times on Sunday about my Nike Pegasus and ON Cloudflow review and the question of why would weight make such a difference in a shoe. ON Cloudflow are 220g and Pegasus 306g. A difference of 86g. If at worst your cadence is 70 cycles per minute per foot. Good is a cadence of 90. That is the number of times you lift your foot off the ground per minute of running. 86g x 70 = 6,020g per minute you lifting per leg per minute. You lifted 6 kilograms of additional weight per foot per minute. Sounds tiring already hey. Now do the math over your 10, 21 or 42km run time. If you racing, planning a PB, then yes, shoe weight does make a difference to your run.
Hope this makes sense.