Dude definitely have and definitely works.
At the studio we have an area that has timbre against the walls designed originally for the application in discussion,however it was a carpeted floor.
Ripped the carpet off and didn't make a drum riser as such,but made an area with timbre flooring.
It has made a big improvement on the way the drums sound overall in our room so I'm in favour off.
And it was inspired by Oz's post ;-)