Do keep in mind that a floating point buffer is 4 times the size of a normal buffer. And an alpha mask can be gray scale, or even one-bit color. Not that this

Do keep in mind that a floating point buffer is 4 times the size of a normal buffer. And an alpha mask can be gray scale, or even one-bit color. Not that this couldn't be a good use of floating point textures for other reasons (A full HDR pipeline for example) But it sounds that using floating point textures is actually the real waste of space.