This is not a DIY machine, just showing that good/commercial machines can be made from wood..
German company Epple, a traditional maker of woodworking benches, also offers a cnc router made completely from laminated european beech. It is a cantileved design with INA slides, this allows full access to the table like a workbench. Of course it has a big footprint..
Rapid speeds are not given unfortunately and neither is the drive system. It looks like servos to my eyes and rack and pinion on the X and Y axis. Ball Screw on Z.
Link to PDF with pictures:
http://www.holz-cnc-epple.de/ho-cnc-100.pdf
I think they use the material they are most comfortable with. Not unlike us mere hobbyists building wooden machines...