I use it for tests and for projects.
I don't have any data to support my claim, but I think MDF does have a tendency to dull bits a little quicker than some woods.
That probably the biggest downside I can think of, but I still intend to keep using it.
I like the stability of it, like you said no warps and twists.
Justin Pierce, aka spalted
*Pattern Editor (Probe) * Centerline * Dxf Import * STL Importer * Version 3 Standalone * Advanced 3D * Advanced 2D * Conforming Vectors * Rotary *C Machine *Rock Chuck