[dnanian]

What I'm saying is that the GUID partitioning scheme allows an HFS+ partition to exist side-by-side with a FAT32 partition. So, you can divide the drive, so your Windows machines can use the FAT32 part, and your Mac can use the HFS+ part.

We don't know how large an image is going to be, and estimating it would take nearly as long as it takes to fail. That said, I'm well aware that the image code could give a warning when you're storing to something that's not HFS+, and it's on my list of things to improve.