560 divided by 47# equals 11.9 grain per pound; divided by 44#, it equals 12.7 grains per pound. Draw length is 27 inches. Smoothness of release can also affect chrono results. Take two grains per inch off the arrow weight and add an inch of draw and 3# of bow weight (and maybe fast flight strings, if they aren't already on the bows) and the 135 fps for the widow would be closer to 170. Kind of whizzing into the wind here though. Either is a good arrow weight and either bow throws them fast enough to do the job. Shoot what you like.