Digitally programmable switching regulator design
There's a general disadvantage for using either - any old MOSFET will have significant drain source capacitance and it might turn your nice regulated voltage into a mess of oscillations because the MOSFET capacitance is messing with the carefully designed feedback regime at higher frequencies. Notice \$C_{FF}\$ - it's beneficial effect at stabilizing the regulator may be be lost (or reduced) with significant drain source capacitance. The good news is that there is still a resistor between MOSFET drain and the FB pin. This offers mitigation.

But, if you choose something with low capacitance (possibly an analogue switch) and low leakage (again an analogue switch springs to mind of the right sort), you should have no bother. Of course, any old MOSFET might just be OK so try it.