[TowerTalk] CM. 43 vs 31

[Jim Thomson]

Im looking at the detailed notes on the  fair rite site.   Im not seeing where type 43 works better than type 31  for freqs above 5 mhz. 
They all depict the opposite.   IE:   type 31 works better than 43  from 160m and all the way up to uhf..around 220 mhz at least.   RS is always higher with type 31. 
What am I missing here ?   

 http://myantennas.com/wp/product/cmc-230-5k/    This uses  4 x type 31 torroids....and RS is sky high from 160-10m. Choking Z is always
a bit higher than RS.  And RS is always higher than  XS. 

Jim   VE7RF.