I’ve only found one clear benefit to a higher PR thus far, my links seem to sell for more when my PR is higher 
.. I can say ranks #1 for blah blah blah and blah.. but if the PR is slippen, so are the link prices .. aside from that.. My PR dropped a point on every site I own this time around, but my rank and therfore income, have both gone up considerably, I’ve never been real sure about wth sandbox is exactly.. but i think this might be me comin out of it 
~LadyH