  An expression for the spacetime absorption coefficient of a scalar field in a
five dimensional, near extremal black hole background is derived, which has the
same form as that presented by Maldacena and Strominger, but is valid over a
larger, U-duality invariant region of parameter space and in general disagrees
with the corresponding D-brane result. We develop an argument, based on D-brane
thermodynamics, which specifies the range of parameters over which agreement
should be expected. For neutral emission, the spacetime and D-brane results
agree over this range. However, for charged emission, we find disagreement in
the `Fat Black Hole' regime, in which charge is quantized in smaller units on
the brane, than in the bulk of spacetime. We indicate a possible problem with
the D-brane model in this regime. We also use the Born approximation to study
the high frequency limit of the absorption coefficient and find that it
approaches unity, for large black hole backgrounds, at frequencies still below
the string scale, again in disagreement with D-brane results.
