Probably should put this in your ask modaco thread really, but is there any chance you can install https://play.google.com/store/apps/details?id=com.jotabout.screeninfo on both the Butterfly J & Xperia Z and get screenshots of both? Would help some developers out looking for this info at the moment.
My only slight annoyance and I do only mean slight, I've got my button brightness level set to about 2 with Paul's app but when I wake up the phone after a notification it goes back to full brightness. Its no big deal but I thought it was worth mentioning. I guess the same would happen with any brightness modification app?