Outwest, my understanding is that a single pump failure will manifest itself as a lower oil pressure.
Sikorsky are currently working on a modification that would give the crew a more obvious indication of pump failure. The modification is a result of the vespel spline problems, etc previously covered.
Currently a single pump failure will result in a pressure of around 5-7 psi. That is enough to allow gearbox operation virtually indefinitely, albeit with a temperature rise.
There is a probability of a new caution being displayed on the EICAS saying MGB PUMP FAIL 1/2 (or words to that effect.)
I'm reluctant to say too much, for various reasons that will be obvious to some here, and will leave that to others who seem equally in touch. What I will say, however, is that there are a number of representatives from the operators' technical pilot community who are actively engaged with the Sikorsky design and Flight Test representatives, on a bi-annual basis, and you can be assured that all of the above topics and many more are discussed vigorously and robustly, with the best of intentions, and a mutual desire to see positive outcomes, on both sides.