I have always had a great deal of respect for the Coach Yard models. Sam Tech is a very reputable builder. They put a great deal of research into their projects. The detail on their cars are awesome from top to bottom. I just wished they were a little quicker with their production and releases vurses the annoncements of a future release. Bottom line is get ready to wait a long time to get it in your hands (I have been waiting a couple of years now for the release of the Santa Fe division superintendent’s business cars).
As far as their locomotives go, I don’t have a clue. I only own passenger cars from them. I would imaginge you won’t be dissappointed with the locomotives either.
Edit: here is a link to their site http://www.thecoachyard.com/ . If you e-mail them they will answer your questions.
I can speak to the latest Coach Yard in general for my Santa Fe cars if that will help. They are very detailed and have a full interior. My diner has plate seetings on the table and are simulated stainless with a high level of detail. I had started building a Santa Fe train several years ago and when the newer ones started getting full interiors and other details, I had to sell some of my previous purchased cars and updated the train with the new ones. They started the pasenger car interiors about four years ago so the level of detail is very good now.
The downside is, the price is much higher now than it was when the cars were just the shell, but the new ones are really nice. One more unwanted feature is the weight of the cars. My Santa Fe train can be pulled by four to six F units and look like the prototype for the passenger era, but some trains might be to heavy for just any head end power. My trains have only run on large club layouts so I am not sure if they will run on tight curves.
I am not aware of any of the Coach Yard locomotives having DCC and sound up to now, but anything is possible. You will however, get a very highly detailed model that you would be proud to run.
Coach Yard has a nice web page for their product list and you can email them.
I have e-mailed them and will see what they say. If the cars are as beautiful as you say I will have to get at least a few. I use 36" curves as a minimum. I hope that will be enough.