They run very nicely and the sound is also very nice, if limited. Mine isn't my best puller, or at least wasn't initially. Someone suggested it might pull better after some run-in. It was tough, unpleasant work, but I did it. I haven't tested it lately, been TDY again. I guess I'll just have to sacrifice and run some pulling tests.....
Actually, I planned to get anSD70Ace too, but their release has been delayed. Now I noticed Tower 55 is planning to come out with all the UP Heritage Schemes. So...I'm thinking I'll wait til I can get the SP Heritage, it looks great.
At present time they only make HO scale locomotives. Here's a link to their web site: http://www.tower55products.com/about/index.php
Don Z.
Research; it's not just for geeks.