I recently brewed a belgian wit that was 40% flaked wheat. I thought it was a lot. I never actually tasted it after it was carbed but my buddy I brewed it for absolutely loved it. He, his daughter and her BF killed the whole keg one night. He said it was incredibly smooth with a big mouthfeel and excellent taste.
12 lbs pilsner malt
10 lbs flaked wheat
3 lbs white wheat
8 oz acid malt
1/2 oz hallertau at 60
1.5 oz saaz at 15
WLP400
That's for 10 gallons. 9 gals 7.2pH strike water. The acid malt put my mash at 5.4 pH.