  The inner radius of the accretion disc around a black hole in the low/hard
state can be measured in one of two ways. Firstly, via the extent of broadening
of the iron emission line, and secondly, from the luminosity and temperature of
the weak soft component seen in this state, assuming it is the disc. We use
both of these methods on all the low/hard state spectra taken in timing mode of
XMM-Newton's EPIC-pn. We find that the two methods are not consistent with each
other, and the difference is not always in a single direction. The two methods
are neither model independent, nor are they independent of current calibration
issues. We find that the remaining small residuals in the EPIC-pn timing mode
response at the <3% level can have a dramatic effect on the fit parameters for
the reflected spectrum. There is also a mismatch in cross-calibration with
RXTE, which makes it difficult to use simultaneous data to extend the bandpass
of the spectral fits. Nonetheless, it is clear from the data that the iron line
is noticeably broader and stronger at higher L/LEdd, which is consistent with
the truncated disc models. We also show that it is likely that the soft
component changes character, from a stable component consistent with a
truncated disc at high L/LEdd, to a variable one with much smaller radius at
low L/LEdd. This adds to growing evidence for a complex soft component in the
low/hard state, possibly resulting from clumps torn from the edge of the
truncated disc.
