Well i don't think that anyone has a DM8 usb in the forum, but i can say this:
The rack is stable. If it is like the DM10 Studio's, it is a great rack. The rubberpads. They are a bit noisy, but they give a good rebound. I prefer the mesh rather the rubber, because it is more "natural" the feel. Tried it not on a DM8, but on a friends DM7. If it is something similar, then for what you search, it is good.
Just one good word of advice. Fill the rack with some material that avoids vibration. The rubberpads send much more vibration, since you hit a solid material. Other than that, you are good to go =)