I'm looking at getting a Midspey Tips or Grandspey Tips for my Redfly 14' 9/10. I looked at the line recommendations on the Rio site and they have listed a 9/10 for both the MS and GS lines. The MS 9/10 is 725 grains and the GS 9/10 is 900 grains. I may not be understanding this right, so why the 175 grain difference between the two lines? Does it have to do with the size of the belly? A rod can only handle so many grains of line so wouldn't you want to stay consistently around the same grain weight regardless of belly size? It also listed a WC 9/10/11 which is 650 grains. How can the same rod cast a 650 gr. WC and a 900 gr. GS? Any advice is much appreciated. Thanks!