On my 3 season Nunatak Specialist I went without differential baffles since the baffle height was slightly under 2". On my winter version, I opted for differential since the baffle height was over 3". With lower baffles the advantage of differential baffling is small, but in loftier ones the circumference difference between the inner and outer layers is much greater. If a quilt is the right size and used correctly, ie. snug against the user, and there is no differential baffling, compression will occur... whether it is an underquilt or overquilt.