There's lots of opinions on rabbit cages. I prefer to keep my rabbits in cages where they can at leastlay down stretched out widthwise, hop several times down the length, and stand up all the way. Are your measurements height x width x length? If so, I'd add one more square of height to your smaller buns' cages, and maybe one to your flemish's cage. I've never seen a flemish in person, so it's hard for me to tell what height he would need. Aside from the height, they seem like really nice cages to me.
I love those grids- you can make any shape/size of cage you want.
p.s. Got any pictures?:wink: I'm a shameless picture addict.