SquidWeaselYay
Ski Diva Extraordinaire
The flex number varies brand to beand so that makes it confusing. As an aggressive skier, with your stats, you should be able to fkex anything 90 to 110 without too much problem. Fitters can soften a boot if it is too stiff. I am 5’2”, 135 lbs, and a nearly 60 year old finesse skier with limited dorsiflexion... and I can flex anything in the 100 range. Is it possible you have dorsiflexion issues? That would also explain why you prefer binding with a slight delta angle. Maybe give heel lifts a whirl.
I have pretty flexible ankles. I can bend my knees down pretty low before my heels come up. No fitter tested it, I looked up some stuff some myself, and think i am good on that front. Heel lifts throw off my fore aft balance. The Lange was super upright with a higher cuff, maybe that contributed to being thrown in the backseat when I would try to get forward, not the flex.