I have a number of Kreg workbenches that I have made with help of their Pocket-hole jig. The workbench tops are made by layering MDF atop a 2x4 frame. I am wondering whether multiple layers of MDF would be effective in holding a bench dog tightly, or would it begin to tear out due to the powdery qualities of MDF?
My bench top is made of 2 half inch pieces of MDF that I laminated together with wood glue and screws. I drilled about 8 holes for my brass bench dogs. I have used those bench dogs for over a year now, when using my hand planes and router, etc. I have never noticed any kind of deformation or loosening of the hold due to the qualities of the MDF.
Also, MDF is cheap, and MDF bench tops are such a great idea in the first place because they can be easily replaced. I wouldn't worry about it if I were you.
There are several workbench designs that include MDF or plywood tops which are thoroughly perforated with dog holes, almost like big sheets of pegboard.
Festool's MFT has a sacrificial MDF top, and the original Paulk Workbench design has a plywood top similarly perforated with dog holes.
If you're simply using bench dogs for clamping, any material should hold up well enough. However, I could see the holes wearing down more quickly if you were to use holdfasts.