Jim have you got a picture of the reverse? Having tried several wall bags over the years I find that the location of the fill point has a huge bearing on how full you can pack 'em and hence how solid you can make the bag. I tend to spend more time on the maize bag currently than the wall bag because of the density but am looking to replace my wall bag as I agree with Glen re the stance training.
Oh and have you got anything slightly less psychedelic?