I am 160-165ish (sorry, too lazy to translate) and I could solo right the Blade with some breeze very easily - the most important aspect is bows to the wind (as Kris said). I have; however, turned over in lighter winds and had to use a righting bag or outside assistance.

Regarding the Viper turtling easy.... That sounds a little suspect, assuming the mast is watertight and you got off the mast pretty quickly (on a slow roll, I'll step on the mast - then on the lower hull)....

I'd love to hear DucatiScott chime in. Otherwise, I'll let you know on March 2 after I turn my Viper over for the first time