I bought my Rivarossi two truck Heisler a couple of years ago and have only now converted the engine to DCC and placed it on my layout.
On DC the engine was a smooth runner, good slow speed control. As my logging/mining portion of my layout is separate from my mainline I thought I would just run it DC. I changed my mind and added a Digitrax decoder to it. An easy job as it has the 8 pin plug installed.
The difference in its running characteristics is terrific. Super slow speed, just crawls if you want it to,
I am very impressed with this engine. I checked with the Riverossi/Hornby site and I am advised that there are no plans to re-release this engine. I am sure it would sell well as there are no other plastic Heislers being offered. Rivarossi has so few engines for the North American market.