First of all, good job on the diesel controller! I like it. Over the years, I can remember seeing a couple of different versions of the cab of a locomotive for running scale trains, one other one that was diesel, one that was steam. Nothing wrong with creating a more realistic controller.
But, back to the idea of having software simulate the operation of a steam locomotive for a scale model - the concept reminds me of the times I have tried to run a steam locomotive on a train simulator type program. Now mind you, I'm no stranger to steam - don't get me wrong, I'm not claiming I'm on the level of Rich or Hot Water, I have a lot of respect for them - but I've ran antique steam traction engines and live steam locomotives since I was a teenager. What I've found out about the simulators... they ain't the same as having your hand on the throttle. Not even close. While they do a fine job of recreating the look of a locomotive's backhead, they cannot do justice to the sounds, feedback and feel of something under steam. I get the same impression when I play a car driving game, or a motorcycle racing game. No matter how good the interface and graphics, it doesn't feel anything like actually driving a car or riding a motorcycle. I can't remember the name of the train simulator program I have, but I get frustrated trying to run a steamer on it... I do boneheaded things I would never screw up in real life, and it seems to be because I am missing visual, audible and tactile clues that I'm used to on a live steam locomotive. I guess I feel like these things on a model locomotive would be as frustrating to me as on the simulators or video games. Yes, it would be a fair attempt to mimic the operation of a steamer, but it still couldn't come close to successfully recreating the experience of being on or actually running the locomotive. But, that's just my two cents, your mileage may vary. And if that is how someone likes to operate their trains, then by all means, use it and enjoy!