Today I brewed a batch of 50% pilsner malt and 50% white wheat flour using my standard BIAB method.
A real adrenaline experience that turned into panic in moments. Although I mixed the flour and grain dry well, large balls formed in the mash, which I kept breaking up, so I extended the mash from the standard 60 to 80 minutes. By the end, the balls had mostly broken or shrunk significantly. However, when I started to lift the bag, there was panic. She took 2/3 of the liquid with her so that she was so heavy that I could hardly hold her, and the squeezing was very slow and difficult. After at least twice as much squeezing time as I usually take to squeeze a bag, I was able to squeeze out most of the liquid, but rather less as much as when I make all-malt beer. I think I will have at least 10% lower utilization than I planned (it won't be more than 65%). At the end of boil, a fatty layer of protein floated on the surface. Washing the bag and brewing pot was also quite a horror. Everything was fatly and much harder to wash. The whole process took about two hours longer than usual and I can say that it is really quite a different experience.
The beer would really have to be exceptionally good to do it again.