Hi Dan,
I'm assuming this is somewhat "tonue in cheek" and partially questioning whether the sim is something worthwhile. You've mentioned that you like to run Eureka on a very limited basis, to preserve a wonderful part of history. Some of us would like to see a lot more of her! In the Sim, we can even be the fireman or engineer. I'd try to be first in line to see her if she does ever get up to Sumpter, although there might be quite a group of us pushing and shoving for position!
I've worked with Jon Davis (the modeler) quite a bit, doing custom sound. He is a spectacular 3D modeler and a serious historian, partial to early locomotives and logging mallets. This is about as accurate as an On3 brass engine, even to working valve gear between the frames.
I'm the creator of the Virtual Sumpter Valley Route for the train sim. Think of it as an unlimited space model railroad that you never have to dust (you do have to defrag the hard drive though). A great deal of research has gone into the route, to make it as close as you'll ever get to 40 miles of the original line. Think of it as an animated historic document.
Speaking of Sumpter, it took a side trip, on CD, to New Zealand, where a friend is setting up the system for meets and activities, then it will be ready for upload to the train sim file library. It will include accurate track and structures from Baker City to Whitney, circa 1935-40. Running the 250 with a tonnage train over Larch is very challenging! The picture is a screen capture at the S-Wye tank, heading to Sumpter.