...I just did the saturated pack experiment with my 30L MYOG frameless pack.
Starting weight: 9.4 oz. Saturated weight (soaking in tub until fully wet out and then wrung out by hand): 16 oz on the nose. After hanging outside for ~20 min (sunny, ~50*) the straps were still soaking, but most of the VX-21 no longer looked wetted out. Weight had dropped to 12 oz.
Front, back and bottom of pack are VX-21. Sides and extension collar are 70D silnylon (coated one side). Shoulder straps and hip belt are VX-21 with 3D mesh. Other straps are flat nylon, and there's a few grosgrain daisy chains.
I realize this is only one data point, but as many others have observed, VX-21 is a great pack fabric. Not sure why more commercial pack makers don't use it.