I found it a bit strange that depending on the site I looked at some gave the same weight for the 4 & 6 ply versions. My AI assistant noted that the ply rating is just a number and that the two ratings could be the same weight. I still believe the lower ply rating would save a bit of weight but I have the 6 ply as the 4 ply was not in stock.
I haven’t done calculated measurements as of yet but the difference in speed over a few flights doesn’t seem to be much i.e. 2 or 3 mph. I can live with that …