Dave, do you have to redraw the whole layout in SCARM or is there a way to convert? I know you are a LOT better at both programs than I, so it's probably fairly easy for you to convert from scratch.
You have to re-enter all the track, but it's not that hard once you're familiar with how SCARM works.
There are many things in SCARM that are nice compared to RRT. For example, if you have a straight section, all you have to do is add the first piece and then press the space bar to add the rest. The same with curves. For example, an oval can be done by selecting only 2 tracks from the library, several presses of the space bar and then copy/past and flip.
The "flip" option is very useful, both horizontal and vertical. Create one reverse loop, copy/paste/flip and you have the other end done. I decided to completely reverse orient a layout in my room once and it was as simple as selecting all and flip, done.
The hardest thing to learn is creating grades, but it's really simple once you figure it out. A lot of it is just reading the documentation and not assuming or expecting things to work the way they do in RRT.
The biggest drawback for me is setting points for polygons. In RRT, I can set specific points in the Properties dialog, not so in SCARM. Most users though probably don't worry about having square buildings or 1x4's that are .75"x35" or 2x4s that are 1.5"x3.5", close enough is good enough for them. 3D bench work design is still easier, quicker and more exacting in RRT. I will say though that being able to add/delete points in polygons in SCARM is also very useful for me, so I do the rough draft in SCARM and the final in RRT, I want 2x4 rails to be 1.5"x3.5"x96", not just close enough.
Plus, when it comes to support, Mixy simply can't be beat!