yeah, I use powdered oats which are considerably higher GI than normal ones.
Howver its my understanding that WM is stellar in terms of an insulin response - nothing else compares. PWO I see insulin manipulation as being my biggest win of the day in terms of hypertrophy.
Plus its out of the belly within 20 mins, and non filling - I like to eat a complex carbs+meat protein meal 30 mins after my PWO shake, with WM im not full at this point.
Personally I cant see any reason not to use it, unless on a keto diet.