I have two also. I have the small and the extra small. They brood 20 and 15 chicks respectively.I now have two. Course one is the neighbors, got to remember to get it back to her.
If I have to brood more chicks than that, I'll pull one of the big Ohio brooders down from the loft.
I was looking at GQF brooders and I was thinking about making something like that.