I've been using Power Pro in my Penn 975 and 965 and have been very happy with the results over the last 2 - 3 years. I only have three spinning reels, light, medium , and heavy and was thinking of respooling my 4400SS with 20lb Power Pro instead of the 12lb on there now. Higher test, more capacity, more abrasion proof and hopefully less line twist. Any down side of casting or plug movement etc..