The trade between the E-N and the SV was indeed the new owners of the E&P trading heavy locomotives for lighter ones better suited for how they saw the operation of the E-N.
The Special Collections in the library of the University of Nevada - Reno has various records from the E-N. One interesting item is that a number of years after the trade the E-N wrote off a locomotive "left behind in Oregon." No further information is provided --apparently with was part of the trade; never shipped to Nevada.
Brian Norden