Open minded?

The Pioneer results are far more likely due to effects associated with the probes themselves than dark matter or alternate gravity theories.

No they have not. In fact they never probably will be. I saw a paper on this a few months ago (sorry cannot remember who by) and it talked extensively about radiation effects on the structure of the probes and some other tiny physical effects and that they might account for the anomaly.By the way, from what I have read - the deviations from GR needed or 'dark matter' required would have easliy shown up in other observations.Certainly the 'dark matter' one is not the cause.GR probably is not the cause. And this will be put to rest soon when Gravity Probe B is launched.That leaves the more obvious and more likely cause to be minor, unforeseen dynamical effects on the probes by radiation, internal stresses/outgassings etc etc of the probes themselves.

System Unavailable This paper seems to conclude no new physics required.I would note that one of the problems of using the Pioneer (or Ulysses and Voyager) probes for investigating new physics in this manner is that they were not dedicated missions designed for this work. It was known all along that such measurements of their dynamics would place constraints on existing physics BUT it was not a mission priority. They were designed primarily for planetary observation and as such included gas thrusters for attitude adjustments etc. and their odd shapes. The problem is that this complicates things due to having to take account of many possible
effects that could contribute to their motions.A dedicated mission for this work would have eliminated these factors and would make analysis much more straightforward.I guess the lesson to be learned is that although the idea of using the probes post observation mission was a good idea - it is difficult (dangerous) to infer things for which they were not really designed for. And to propose new physics for the anomalies is on shaky ground to say the least.