  We study the reliability of extractions of |V_{us}| based on flavor-breaking
hadronic tau decay sum rules. The ``(0,0) spectral weight'', proposed
previously as a favorable candidate for this extraction, is shown to produce
results having poor stability with respect to s_0, the upper limit on the
relevant spectral integral, suggesting theoretical errors much larger than
previously anticipated. We argue that this instability is due to the poor
convergence of the integrated D=2 OPE series. Alternate weight choices designed
to bring this convergence under better control are shown to produce
significantly improved stability, and determinations of |V_{us}| which are both
mutually compatible, and consistent, within errors, with values obtained by
other methods.
